I am quite unimpressed with this developers update approach.
I bought LockScreen when it came out and stopped using it after only a week or two. It was unreliable when trying to unlock, sometimes failing to recognise the pass pattern.
Now I see there is a new version in the Mac App Store but no upgrade path. In fact "LockScreen" is no longer available and there is a 'new' app called "LockScreen 2". Sure, it's only a couple of bucks but it's also been a scant three months since the first version that, in my experience, didn't work properly.
You can do this for free by using Keychain Access. Open Keychain Access (in your Utilities Folder, which is in your Applications folder), and go to preferences. Check the box for Show Status in Menu Bar. You will now see a Padlock in your Menu Bar, click and hold, you will now see a Lock Screen option, select and release. Your screen will now lock, and will need your computer password to open.