android finish() method doesn't clear app from memory
Android keeps processes around in case the user wants to restart the app, this makes the startup phase faster. The process will not be doing anything and if memory needs to be reclaimed, the process will be killed. Don't worry about it :)
Best way is firstly use finish() and after that use System.exit(0) to clear static variables. It will give you some free space.
A lot of applications leave working processes and variables what makes me angry. After 30 minutes of using memory is full and i have to run Task Manager - Lvl 2 clear memory
Its not true that is cousing problems i've tried it for over 3 years in my apps. Never get crashed or restart after using Exit()