[Philipp Yeo]

So, when I open, let's say 14 apps and open task manager, it only shows 13. Is there a limit to how many apps you can open? Or is something else closing the apps discretely?

I have the following apps that might be able to do this: Widget locker, Google Now.

P. S. It just became 9 as I was writing this. Wut.

[Golfdriver97]

Android does self manage apps. If there is one of the older apps that it need RAM from to keep operating, it will shut them down. It also depends on which app was used most recently for resources. If Android needs a lot of resources to run, say, a Star Wars game, and needs to kill 3 apps to get the RAM it needs, it will do that.