How do I use the wpmu dev dashboard functions?

I have just bought the 1-year membership for the 50% discount and installed the wpmu dev dashboard on one of my sites. The thing is that I am asked to upgrade in order to use the features. The API key was automatically entered when I logged on to my account. I also tried to edit it and logging on again to see if this helped but nothing changed. The question is thus how do I prove the membership and use the functions?