It’s worth thinking of computer memory less like a resource that’s used up, like water being scooped out of a bucket and drank, and more like sand in a sandbox.

Sometimes it’s being used for something meaningful, like being a castle or making the walls of a big hole or having letters written in it, and sometimes it just lying around doing nothing, but there’s not any more or less of it.

You might draw a line around a bit and say, “my castle is here, don’t use anything inside the line”, and at the end of the day you rub the line out and go, “I’m all done now, so do whatever”. Maybe you come back and the castle is still there or maybe someone has knocked it down and built something else with it.