user4841: I have seen multiple references to karma on this site, varying in its descriptions dependent on the question. 
Most answers appear to have the same answer e.g. Whereas Karma is what happens as a result of your actions or your choices. - Source
If karma is the result of my actions or choices and it has a bearing on one's life now and in the next, who/what is the keeper of such actions and choices? Another way to ask the question is how is a record of my actions maintained and kept?

user5154: The kamma is stored in the subconscious as a resultant consciousness (vipaka citta) and remains there until a right condition present itself, when it would resurface. If it is strong it would be carried over to the next existence.
More on the transmigration of kamma in the Theravada tradition.

user5123: Firstly, I would like to clarify that according to Theravada Buddhism, karma is not the 'result' of your 'actions' but the action itself. Performing certain kinds of actions (karma) leads to certain kinds of results. 
What does ‘action’ mean? It exclusively means ‘intention’, in the context of Theravada Buddhism. The physical doing of something is equated with karma only insofar as that it is a physical manifestation of the intention.
With the above clarification, the question would be interpreted to mean ‘Who/What/How is the keeper of intentions’? The question is assuming that there is some kind of ‘keeping of intentions’ that occurs between the moment of intention and result. This assumption is wrong, and may be based on popular theories or misinterpretations of karma and how it leads to certain results.
So you might now ask, how does a specific intention lead to a specific result? The theoretical answer is quite complicated, and can be found by reading thoroughly the text called Abhidhamma (here is a link to an English translation: http://www.buddhanet.net/pdf_file/abhidhamma.pdf), which is the primary source of Theravada Buddhism where the subject of how specific karma leads to specific results is examined in detail.
However, my personal suggestion is that it would be a wise decision to understand for yourself how specific intentions (karma) leads to certain results, rather than trying to have an intellectual understanding of this process by reading the text. Having a practical understanding of this process of cause and effect (how karma works) is far more beneficial than having an intellectual understanding, because an intellectual understanding is simply based on concepts and is essentially meaningless apart from giving you a temporary sense of satisfaction whereas if you see how cause and effect works for yourself, it will lead you to being released from your mental defilements and therefore set you free from suffering permanently (the path that the Buddha taught). 
So now you might ask me, how can you understand cause and effect for yourself? By understanding the experience of reality clearly. How can you understand the experience of reality? By practising the four foundations of mindfulness. 
If you want to know how to practise the four foundations of mindfulness, please read this book (http://static.sirimangalo.org/howto/HTM.pdf) written by a great monk called Yuttadhammo, who in this book clearly and comprehensively explains how to practise the path that the Buddha taught in order to understand reality clearly and therefore set yourself free from suffering.
Therefore, by practising the path that the Buddha taught, you will come to understand for yourself the nature of karma, how it is not something that is recorded and how it actually leads to specific results.

user295: When a volitional thought comes Sankara is created. This in the subtlest forms this is Kalapa (Sub atomic particles which arise and pass causing other sub atomic particles to arise when they pass). Say when you are doing some action you feel the sensation associated with the action (p35 - Comprehensive Manual of Abidhamma by Bikkhu Bodhi) based on roots of the action.
These ("seeds") stay dormant until the condition are right for them to give results. Here multiplication starts ("fruit"). When this happens you feel the associated sedations of the results. Each seed has a certain "taste" associated with the result (the same "taste" you felt when doing the action). By your reaction to this sensation (with craving or aversion) you multiply the results of future results.
When a new group of Sankara or seeds starts when these have the dominant taste off your past Karma and other Sankara lay dormant though still arising and passing as a group of Kalapas. Since this arising and passing is with decay if a condition does not come for its multiplication then some just passes away with no results.
Through meditation but making you self sensitive whilst not being reactive to the sensations associated with the formation you stop reacting new conditioning and also understand the process these are created. You might not be able to identify each and every Kalapa (only a Buddha can do this if I am not mistaken) which sums up as you total Sankara but you will identify more and more significant clusters. These might be small dot like areas where a certain sensation prevails where as maybe in the rest of the body other sensation are dominant. (These are also fruits due to some multiplication of the seeds as they maybe too minute for a normal person to identify.) By non reaction (devoid of craving and clinging) they loose there potent as they do not multiply.
At the moment of death what happens is this process passes away in one physical body an arises in another. Hence the seeds are still there whilst arising and passing.

Another way to look at this is in the process of doing Karma you create a cluster of Kalapas. This arise and pass giving arise to other Kalapas. When one Kalapa passes it creates a new one which is progressively less potent. Look at this as a Discrete-time Markov process.
Karma is a memoryless process (hence no keeper). You have hidden states not observable over a threshold (based on strength of awareness). There are external perturbation (result of past Karma, hence contact with the taste pertaining to the state) based on the potent of the hidden states to which you react and cause them to (state based on response to stimuli) multiply the hidden states. Each state has a stopping time when they decay away without result. 

user18: The Sanskrit word karma means action. It was used in Brahmanism to refer to those physical and verbal acts that were considered to bring positive results to the individual performing the acts (or on behalf of whom the acts were performed by Brahmin priests).
The Buddha denounced this idea. In his teaching, that which was potent for the individual was the state of mind (cetana):

cetanāhaṃ, bhikkhave, kammaṃ vadāmi
It is cetana, monks, that I call karma. 
-- AN 6.63

Either way, anyone who tells you that "Karma is what happens as a result of your actions or your choices", doesn't understand the meaning of the word. What they are referring to is vipāka (result); karma is that which brings vipāka.
Either way, your question still stands:

who/what is the keeper of such actions and choices? 

This is a common question, but it mostly stems from a lack of clear understanding that karma simply means action. It isn't a thing, it doesn't last from life to life or moment to moment, and it certainly doesn't come back to reward or punish the doer.
The law of karma is simply an observable pattern or regularity that exists between ethical acts and the results that follow them. I don't know of any explanation for why the universe works this way, but that it does is readily apparent. 
We don't question, for example, whether torturing others is bad for the person doing the torturing (or at least we shouldn't). Obviously doing evil corrupts one's mind, destroys one's reputation, cultivates enmity, etc. (c.p. MN 129)
The real question, I guess, is why this doesn't end at the moment of death. Of course, given that death of the individual is a concept (as is the individual), there really isn't as much trouble explaining this as one might think. One's rebirth is conditioned by one's death and the events leading up to one's death; a murderer is likely to be reborn entangled with the murdered, because murdering others involves karmically potent mind states that change one's future mind states including those involved with one's death.

Another way to ask the question is how is a record of my actions maintained and kept?

It isn't. Nothing that arises lasts more than a moment, and nothing that has ceased ever returns. Karma is simply a natural law, like the law of gravity or conservation of energy, that:

“yādisaṃ vapate bījaṃ, tādisaṃ harate phalaṃ.
  kalyāṇakārī kalyāṇaṃ, pāpakārī ca pāpakaṃ.
Whatever sort of seed one plants, that is the sort of fruit one will reap;
  A doer of good good, and a doer of evil evil. 
-- SN 11.10


4841: <p>I have seen multiple references to <code>karma</code> on this site, varying in its descriptions dependent on the question. </p>

<p>Most answers appear to have the same answer e.g. <code>Whereas Karma is what happens as a result of your actions or your choices.</code> - <a href="https://buddhism.stackexchange.com/questions/5371/fate-and-karma-same-or-different">Source</a></p>

<p>If karma is the result of my actions or choices and it has a bearing on one's life now and in the next, who/what is the keeper of such actions and choices? Another way to ask the question is how is a record of my actions maintained and kept?</p>
 5154: <p>The kamma is stored in the <a href="http://himalaya.socanth.cam.ac.uk/collections/journals/bot/pdf/bot_09_01_01.pdf" rel="nofollow noreferrer">subconscious</a> as a resultant consciousness (vipaka citta) and remains there until a right condition present itself, when it would resurface. If it is strong it would be carried over to the next existence.</p>

<p>More on the <a href="https://buddhism.stackexchange.com/questions/9154/what-are-the-positions-of-the-different-schools-on-a-primordial-mind">transmigration of kamma</a> in the Theravada tradition.</p>
 5123: <p>Firstly, I would like to clarify that according to Theravada Buddhism, karma is not the 'result' of your 'actions' but the action itself. Performing certain kinds of actions (karma) leads to certain kinds of results. 
What does ‘action’ mean? It exclusively means ‘intention’, in the context of Theravada Buddhism. The physical doing of something is equated with karma only insofar as that it is a physical manifestation of the intention.
With the above clarification, the question would be interpreted to mean ‘Who/What/How is the keeper of intentions’? The question is assuming that there is some kind of ‘keeping of intentions’ that occurs between the moment of intention and result. This assumption is wrong, and may be based on popular theories or misinterpretations of karma and how it leads to certain results.</p>

<p>So you might now ask, how does a specific intention lead to a specific result? The theoretical answer is quite complicated, and can be found by reading thoroughly the text called Abhidhamma (here is a link to an English translation: <a href="http://www.buddhanet.net/pdf_file/abhidhamma.pdf" rel="nofollow">http://www.buddhanet.net/pdf_file/abhidhamma.pdf</a>), which is the primary source of Theravada Buddhism where the subject of how specific karma leads to specific results is examined in detail.</p>

<p>However, my personal suggestion is that it would be a wise decision to understand for yourself how specific intentions (karma) leads to certain results, rather than trying to have an intellectual understanding of this process by reading the text. Having a practical understanding of this process of cause and effect (how karma works) is far more beneficial than having an intellectual understanding, because an intellectual understanding is simply based on concepts and is essentially meaningless apart from giving you a temporary sense of satisfaction whereas if you see how cause and effect works for yourself, it will lead you to being released from your mental defilements and therefore set you free from suffering permanently (the path that the Buddha taught). 
So now you might ask me, how can you understand cause and effect for yourself? By understanding the experience of reality clearly. How can you understand the experience of reality? By practising the four foundations of mindfulness. 
If you want to know how to practise the four foundations of mindfulness, please read this book (<a href="http://static.sirimangalo.org/howto/HTM.pdf" rel="nofollow">http://static.sirimangalo.org/howto/HTM.pdf</a>) written by a great monk called Yuttadhammo, who in this book clearly and comprehensively explains how to practise the path that the Buddha taught in order to understand reality clearly and therefore set yourself free from suffering.</p>

<p>Therefore, by practising the path that the Buddha taught, you will come to understand for yourself the nature of karma, how it is not something that is recorded and how it actually leads to specific results.</p>
 295: <p>When a volitional thought comes <a href="http://en.wikipedia.org/wiki/Sa%E1%B9%85kh%C4%81ra" rel="nofollow">Sankara</a> is created. This in the subtlest forms this is Kalapa (Sub atomic particles which arise and pass causing other sub atomic particles to arise when they pass). Say when you are doing some action you feel the sensation associated with the action (p35 - Comprehensive Manual of Abidhamma by Bikkhu Bodhi) based on roots of the action.</p>

<p>These ("seeds") stay dormant until the condition are right for them to give results. Here multiplication starts ("fruit"). When this happens you feel the associated sedations of the results. Each seed has a certain "taste" associated with the result (the same "taste" you felt when doing the action). By your reaction to this sensation (with craving or aversion) you multiply the results of future results.</p>

<p>When a new group of Sankara or seeds starts when these have the dominant taste off your past Karma and other Sankara lay dormant though still arising and passing as a group of Kalapas. Since this arising and passing is with decay if a condition does not come for its multiplication then some just passes away with no results.</p>

<p>Through meditation but making you self sensitive whilst not being reactive to the sensations associated with the formation you stop reacting new conditioning and also understand the process these are created. You might not be able to identify each and every Kalapa (only a Buddha can do this if I am not mistaken) which sums up as you total Sankara but you will identify more and more significant clusters. These might be small dot like areas where a certain sensation prevails where as maybe in the rest of the body other sensation are dominant. (These are also fruits due to some multiplication of the seeds as they maybe too minute for a normal person to identify.) By non reaction (devoid of craving and clinging) they loose there potent as they do not multiply.</p>

<p>At the moment of death what happens is this process passes away in one physical body an arises in another. Hence the seeds are still there whilst arising and passing.</p>

<hr>

<p>Another way to look at this is in the process of doing Karma you create a cluster of Kalapas. This arise and pass giving arise to other Kalapas. When one Kalapa passes it creates a new one which is progressively less potent. Look at this as a <a href="http://en.wikipedia.org/wiki/Harris_chain" rel="nofollow">Discrete-time</a> <a href="http://en.wikipedia.org/wiki/Markov_process" rel="nofollow">Markov process</a>.</p>

<p>Karma is a memoryless process (hence no keeper). You have hidden states not observable over a threshold (based on strength of awareness). There are external perturbation (result of past Karma, hence contact with the taste pertaining to the state) based on the potent of the hidden states to which you react and cause them to (state based on response to stimuli) multiply the hidden states. Each state has a stopping time when they decay away without result. </p>
 18: <p>The Sanskrit word <em>karma</em> means action. It was used in Brahmanism to refer to those physical and verbal acts that were considered to bring positive results to the individual performing the acts (or on behalf of whom the acts were performed by Brahmin priests).</p>

<p>The Buddha denounced this idea. In his teaching, that which was potent for the individual was the state of mind (<em>cetana</em>):</p>

<blockquote>
  <p>cetanāhaṃ, bhikkhave, kammaṃ vadāmi</p>
  
  <p>It is cetana, monks, that I call karma. </p>
  
  <p>-- AN 6.63</p>
</blockquote>

<p>Either way, anyone who tells you that "Karma is what happens as a result of your actions or your choices", doesn't understand the meaning of the word. What they are referring to is <em>vipāka</em> (result); <em>karma</em> is that which brings <em>vipāka</em>.</p>

<p>Either way, your question still stands:</p>

<blockquote>
  <p>who/what is the keeper of such actions and choices? </p>
</blockquote>

<p>This is a common question, but it mostly stems from a lack of clear understanding that karma simply means action. It isn't a thing, it doesn't last from life to life or moment to moment, and it certainly doesn't come back to reward or punish the doer.</p>

<p>The law of karma is simply an observable pattern or regularity that exists between ethical acts and the results that follow them. I don't know of any explanation for <em>why</em> the universe works this way, but that it does is readily apparent. </p>

<p>We don't question, for example, whether torturing others is bad for the person doing the torturing (or at least we shouldn't). Obviously doing evil corrupts one's mind, destroys one's reputation, cultivates enmity, etc. (c.p. MN 129)</p>

<p>The real question, I guess, is why this doesn't end at the moment of death. Of course, given that death of the individual is a concept (as is the individual), there really isn't as much trouble explaining this as one might think. One's rebirth is conditioned by one's death and the events leading up to one's death; a murderer is likely to be reborn entangled with the murdered, because murdering others involves karmically potent mind states that change one's future mind states including those involved with one's death.</p>

<blockquote>
  <p>Another way to ask the question is how is a record of my actions maintained and kept?</p>
</blockquote>

<p>It isn't. Nothing that arises lasts more than a moment, and nothing that has ceased ever returns. Karma is simply a natural law, like the law of gravity or conservation of energy, that:</p>

<blockquote>
  <p>“yādisaṃ vapate bījaṃ, tādisaṃ harate phalaṃ.
  <br/>kalyāṇakārī kalyāṇaṃ, pāpakārī ca pāpakaṃ.</p>
  
  <p>Whatever sort of seed one plants, that is the sort of fruit one will reap;
  <br/>A doer of good good, and a doer of evil evil. </p>
  
  <p>-- SN 11.10</p>
</blockquote>
