I'm not really familiar with adobe effects so it might be a dumb question. When I'm having fun following tutorials and messing with effects, AE's ram usage keeps going up(of course). But it keeps going up infinitely, and closing project doesn't change the situation, so I have to turn the program off and on to free up ram space. I tried reducing undo preference(I'm not sure if this actually matters) but no difference.
I feel really stupid to reset program periodically to reset ram. So, Is this normal behavior for after effects?
It's not normal. Unlike Photoshop, AE should purge unused memory since once you close a project, there is no way to go back, anyway. On the other hand, of course AE uses all sorts of cacheing and tries to keep them for as long as possible, so purging some parts of the memory only happens when you e.g. create a new RAM preview. in any case, feel free to make good use of the Edit --> Purge function. If the issue is more serious, this could be a leaky effect, a likewise atrocious CoDec or even graphics card issues, but we can't know...
Purge function is just great. Thank you! Still the problem remians, but at least I don't have to reset AE.