How to track application launches?

Question

Android

There is an idea for one application, something like AppLock. When other applications are launched, certain actions are performed. I rummaged through the whole Google, including the English one, and I did not find any ways other than reading logcat. For example, in such applications Clean Master and Hexlock, you need to put some permission in "Apps with access" to work. What is this permission, how to put it on your android application and do you know any other ways to track the launch of applications?