Only three stars, because it's easy to circumvent in many cases: just change the app's bundle ID in the nested Info.plist. If after that modification macOS (not Lock/LockPro) doesn't let the app launch, remove the quarantine XA or even apply a new code signature. So Lock & Lock Pro are only really useful for applications that have certain protections, e.g. system apps like Mail, Safari or Messages (which you can't modify, and which probably wouldn't launch, even if you *could* modify them), or certain apps with elevated privileges, e.g. apps access to your Mail folder. (You might still unlock those, but you'd need a proper new code signature for that.) But all that doesn't mean it's worthless… being able to protect Mail & Messages is definitely a plus.