Changing your Arma 2 OA CD-Key

I have just purchased Arma 2 OA from Gamefly to get another legit CD key for testing my new bypasser project with Ardivaba, I'm wondering if I can possibly get the cd key from this game WITHOUT having to download it. When I look through the settings it only shows me the product key which is formatted as:

XXXX-XXXXX-XXXXX-XXXXX-XXXXX

many threads, would appreciate a link.

p.s. I have read many of them and none of them tell me how to get my cd key from a product key or from gamefly without downloading the game, only when you know your cd key you want to change it to, however they do tell you your current cd key (useless to me) however, after 4.6k posts I'm sure you've learnt to skim instead of actually read and answer the question since you can now post again 2-3 times to answer my beginning question.