I always misplace activation codes for operating systems I'm using/testing in VirtualBox. As a workaround, I've started keeping the codes in the filenames themselves. For instance, after downloading the free Windows 7 RC1 to test in VirtualBox, I pasted the long activation key as the filename of the ISO disc image, and just added Win 7 RC1 at the end.
A simple tip, but one that's saved me from having to add such details to a separate permanent storage solution.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090514042927670