Ill be submitting a "problem" with this app to Apple.
This is a clear case of nagware, something were not supposed to see on the app store.
The other day I did more than just use the app for a few minutes...about 30 minutes.
My book was interrupted by a commercial from the app developers indicating that I needed to cough up $2.99 to get rid of the nag message. I got through their message and continued with my book only to be interrupted again within a few minutes.
Aljmc about Audiobook & Podcast Player, v1.02