As the description of this app makes plain, this is NOT a printing app, it is a compatibility testing app. To avoid wasting paper, only load a few sheets. Another hint for the 1-star reviewers that dont read descriptions: DONT test it with your expensive photo paper!
Why would you buy the full app? If you have a perfectly good but older printer that doesnt have AirPrint built in, this helps you leverage your existing printer. I have an older Samsung laser printer that doesnt have AirPrint but that I can still use from my iOS devices. Rather than shelling out a few hundred for a new laser, I can pay $7 to use my very good quality existing printer.
VancouverJavaMan about Printer Pro Lite by Readdle