Multiwinia, why won't you let me play?

[ríomhaire]

So I got a Multiwinia demo a while back and played the three maps available to me happily. Everything was fine until I bought the game a few days ago in a Zavvi closing down sale. So I install the full game and load it up, finding it a little odd that it didn't ask me to enter the CD key that's printed on the back of the manual. When I started up the game, it still says I'm a demo user. I go into the authentication menu and it won't let me enter any CD-key. How do I unlock the full game?

[Reflex]

Should have used Steam.

[Eejit]

Uninstall the demo and game, reinstall the game.

[ríomhaire]

Tried that, several times. Still isn't asking me for CD key and says it's a demo.

[Eejit]

Hmm tried checking the registry see if there are any entries left over that you should remove?

[ríomhaire]

Folder is empty. Would there be anywhere else that the game might store files?