I did use the installation code when i installed C6Pro, and when it came time to upgrade I clicked on the WEB button up on the top left-hand side of the screen and clicked on Register, then I re-entered the C6Pro installation code and it took. Then I got a little window that said "Thank you for registering". I checked my account at DAZ and it showed my other past purchases, and also "unknown app", which i figured must be the C6Pro.When I put C7Pro in my basket and checked out, there were no problems or questions at any time. Installation was a breeze.