Do turtles generally have good memory?

I have a baby snapping turtle and a grown red eared slider. They both live in the same tank for over 2 years and have been getting along pretty well and from my point of view are "friends". When the snapper needs help to reach the air, he uses the res shell for support.I am aware that when snappers get bigger, they become more aggresive. So i want to know if they will still coexist for the next ten years? Thank you.