Chris,
In the demonstration mode you can do all edits and save your design provided you should be in the limits, the limits for the PADS Layout can be found at File->Reports->Limits.(open the report in demonstration mode, not in the licensed mode)
If you are in this limits you can even export your gerbers.
If you open the software in demo mode and if you plug the dongle, you need to restart the software to open in the licensed mode.
and if you are working in the license mode and if you unplug your device, you get a warning saying like this after some time(software will check for dongle at regular intervals), and if you click cancel , PADS will create a backup of the current design and exits. if you click retry it again checks for the dongle and will give the same message if it could not find one.
hope it helps
