This application is, as its name clearly suggests, a program that helps you unlock password-protected PDF documents. The program might prove to be of good use if you forget the editing or printing password that you've previously set for a PDF file and require assistance in breaching the security settings.
All you need to do is to drag-and-drop the password-protected file onto the app's main screen and the program will provide you with the output you require within seconds. Then, you can start editing the PDF document or print it using a third-party app installed on your Mac.
The app features two unlocking methods (normal and brute force) that use different Apple APIs. The first unlock mode should do the trick in most cases while the second uses old APIs and converts the PDFs to image files.
Unfortunately, on the homepage of the developer it's stated that this application can't unlock PDFs that require a password to be opened. It can only breach security settings for PDFs that have printing or editing passwords.
As a conclusion, I'd say you should try this application only if you wish to unlock PDFs with print or edit passwords. The program is very simple to handle, immediately offers you the results you require, and it's free of charge.