Memory Problem

Hi guys, I have a simple game project set up and when I play it in editor right after I launch Unreal, this is what my memory usage and objects count look like:
After playing it in the editor a dozen times for testing purposes, the numbers increase gradually to 2500mb of used memory and up to 100k objects.
As far as I know, when the game is closed, everything gets destroyed and the memory is wiped afterwards so why is this happening? Is it normal for the development build? How can I fix it if it is abnormal?