AppLock is a free Android app that comes with a lot of options. You can pay for it, get premium features, and no advertising. Or you can view advertising, get the premium features, and not pay anything. Finally, you can use it ad-free, but without premium features. The choice is yours. The app itself is a simple, but powerful app that allows you to lock your apps up tight with passwords so that snooping eyes can’t see them.
This is great if you have nosy roommates, kids, or if you just want some piece of mind. You can use the app for free with or without ads (your choice). The ad-free version has a few features missing, but the ads will unlock those features as though you paid for it.