Page Lock was released about a year ago. While it worked great, it lacked some features and need some styling.
I really thankful for confday (by @gillesvauvarin) support which allowed me time last week to make Page Lock what I always wanted it to be!
The installation proccess has been simplified and now you can also lock login-protected pages on the front-end (yet to be documented).
Check out the docs for installation guide, basic usage and to learn about available options.
If you also want to support the development of Page Lock, you can donate via PayPal.
Try it and let me know what you think