What happens to files created with the Prism demo when it expires?

When you uninstall Prism (full or demo) you will not delete the files you created with Prism.

With iPhones and iPads, data saved by an app are often associated with that particular app, and in many cases will be lost when the app is removed from the device. For this reason, some people are afraid that uninstalling the Prism demo will also remove the files saved by the demo. This is not a problem. 

Windows and Mac computers work differently than iPhones and iPads. When you save files from Prism (either the full program or the demo, either Mac or Windows), you choose the file name  and you choose which disk and folder it is saved into. The files are identical regardless of whether they were saved with the full program or the demo. You can rename, move, email, delete, backup, etc. all using Windows or Mac tools that are the same for all files (and are independent of Prism).