Q:

Running out of Memory while installing SPB Shell 3D APK

I am using LG P500 phone, running Android 2.3 (Gingerbread).
I am installing SPB Shell 3D APK file which I got from internet.
After some time it shows error that Memory Full, Please Uninstall Some Apps to Free Memory
Though I have 50 MB Free memory.

A:

50 MB is not much. Consider that for installation, the apk gets probably temporarily stored there (in /data/local(not always sometimes it's in the /cache/download/ folder) -- at least that's what the playstore app does, I'm not sure about a "local install" where the .apk probably is available from your sdcard) for processing, then gets installed (below /data/app) and initializes its data (below /data/data). And during all that, it should leave enough free space to allow all other apps to work normally: Creating temporary files, log files (at least the latter again being stored below /data in many cases, e.g those you can access via logcat), and manipulate their data (guess where -- yes, again below /data/data).
So you see: Most of these actions take place on the /data partition. Now look what size the .apk of SBP Shell 3D has. Something about 10..15 MB? So when installed, it creates its data structure below /data/data as well, which adds to this. And during all that installation process, free space probably falls below 30 MB (if it really requires a copy in /data/local for the install, even below 20 MB) -- which is why the system alerts about "free space getting low".
The solution already came with the warning: Uninstall some apps. Or move some bigger ones / rarely used apps to SD, if possible. Or clean up some cache -- but that will only help temporarily.
You might also want to check some other space/installation related questions here:

Why is “insufficient storage” wrongly reported when installing an .apk via adb?
Is there a way to workaround the phone memory limit for installed apps?
Why can't I install apps when I have enough storage?
Application doesn't get installed : insufficient storage available

could be good starting points.

