I have a free app that distributes paid digital content via in-app purchases for different event planners to event attendees through the App Store. I’d like for event planners to sell access/accept payments of their digital content on their site during attendee event registration rather than through the App Store. My app would still be required for content distribution. Can this be done without breaking App Store rules? My point isn't trying to skirt around paying Apple, but my event planner clients would prefer their payments are taken/received during registration.

Newbie app developer here. Is there a way to be notified via email or other means when my app has been purchased?