I want to spend the $9.99 to upgrade to Pro but I can't find the download link. Where do I go to download the Professional version?
You make the in-app purchase from within 1P5 for iOS itself. There's a helpful article in the user guide here which includes a section on how to do it.
@trico21: Sorry for the confusion, but I'm glad to see that Stephen_C has you covered!
We decided to go with a free app for version 5 so that people can 'test drive' it or just use it as a reader without having to make a purchase, and then 'unlock' the Pro Features later if desired. Cheers!