SMH...
Who are these people that can't keep their fingers off of other people's phones? Who are these people who can't control their own property?
If you need to lock anything other than the screen at wake up, you need to associate with better people. It's not about protection from theft. It is protection from nosy people...
Honestly, I don't get this perpetual "I need an App lock" issue. If it is your parents; too bad, they are the boss of you. If it is your spouse or girlfriend or partner or crush or buddy with benefits - tell them stop it or they are gone. If it is your friends, smack them on the hand really hard and tell them, "No no, baby. Fire burns you. Baby must not touch."