Sorry about the trouble. Do you have your original TF registration email? That has the link where you need to download the Full version from.
The DEMO accepts codes, but cannot be registered.
This happens enough (understandably) that I'm going to make a note to have a box popup in the DEMO if you've previously entered a name/code.
If you don't have the email, drop us a line at support AT topofusion.com and we'll send it to you.