If you're talking about your activation key, you can't change it. The code is directly linked to your id and changing it would break the system. It adds a whole new amount of complexity that badspot probably wouldn't want to deal with.
Just make sure you don't let others read your email, don't store the key in a text file (my friend got his stolen that way), just use your email as storage. You could even delete the email since you can get your key resent. If a keygen was somehow created that caused many users' ids to be stolen, I'm sure badspot would come up with a solution for the situation.