click reactive by mistake..how to re-active my current Macbook

hi, 

I sign up a 30 days free trail of Office 365, and install office 2011 for mac successfully on my macbook.

But I click reactive button by mistake.....

Now, I can't connect skydive by microsoft document connection.

But all applications works fine.

So, how do I add my current macbook to the active list again?

Thanks very much!

Neil