Since this isn't the ideal solution, we've added the iCloud storage option. If the app is ever deleted, your files are deleted, as well. If you are using SketchBook Pro Mobile on iOS, the files are saved within the Gallery, which is part of the app. This means if the app is ever deleted, your sketches still exist elsewhere.
Some versions of SketchBook save your files on the device or machine in a separate folder for the app.
