user27755: Can a smart contract be created which can be exchanged once at point of sale, and only transferred subsequently through a single approved exchange? Can that be written into the contract itself?

user24925: Bitcoin script only allows the conditions under which an output can be spent to be controlled, it does not provide a method for dictating what can happen to the output once these conditions have been satisfied. The concept you are describing is called a coin covenant, the linked thread goes into some detail explaining why this is generally a bad idea. 

27755: <p>Can a smart contract be created which can be exchanged once at point of sale, and only transferred subsequently through a single approved exchange? Can that be written into the contract itself?</p>
 24925: <p>Bitcoin script only allows the conditions under which an output can be spent to be controlled, it does not provide a method for dictating what can happen to the output once these conditions have been satisfied. The concept you are describing is called a <a href="https://bitcointalk.org/index.php?topic=278122.0;all" rel="nofollow">coin covenant</a>, the linked thread goes into some detail explaining why this is generally a bad idea. </p>
