This is about the behavior when you cancel the subscription of the expert and the expiration date has expired.
The expiration of the expert does not affect any data already stored in the app. If you cancel your subscription when it expires, the app will automatically revert to the free version and you will not be able to use the expert features, but you will still be able to view all the data already saved in the app. (It will not automatically disappear).
Also, since MyPics is a photo viewer app, not a cloud service, all data is stored in the device. Therefore, all data can be retrieved at any time via iTunes file sharing, etc., regardless of billing status.