It would lock Gallery only when you choose to lock. If you forgot the password you set before, please refer to the following steps
* If the title in the upper-left corner on Gallery is "AppLock", please go to Google Play and uninstall "ASUS Launcher". You can reset your password and enjoy the "Lock Gallery" feature after upgrading "ASUS Launcher". Don't forget to set a Google account to retrieve your password if forgetting it again.
* If the title in the upper-left corner on Gallery is "CM Applock for ASUS", please click the upper-right button and choose "Forgot password?". After entering the password of your Google account, you can reset your password to lock Gallery again.