There is no guide on how to use the application, but it should be pretty straightforward if you already know the PHP language. Secondly, I have checked its description but found nothing about decryption. There is also no specification about the type of encryption used in the application and yes, the popup will be removed if you purchase the full version, but there is a problem here as well because no official website could be found.
Check other applications from this category: http://software.informer.com/search/php+encryption