
What version of the app are you using? What aircraft are you using? What mobile device are you using?
If you are using a KMZ Export only aircraft it is limited to 200 waypoints/images per flight. Aside from that, there are not tier-based limitations on how many images can be taken during a flight.
You can create flight boundaries or linear paths using Google Earth to create KML files and import those into Map Pilot Pro using the File Manager.