I realized that applock iso useless. If my phone is stolen, they can just uninstall bitdfender app to gain acess to the apps.
Is there a way to prevent the app from being uninstalled?
Open your Bitdefender Mobile Security for Android, go to "More", in the new opened menu click on your account (your name and e-mail) and then click on "Uninstall Bitdefender Mobile Security".
A new pop-up window will open with text "Enter PIN to confirm".
And that PIN is actually the PIN you already set for the "App Lock" module, during the installation of the app on your phone.
Without entering the PIN, it is impossible to uninstall the app.