Any time you buy software it has a serial key that is locked to that disc, not to say that another key will not work cause it will, but if you have lost yours you can try to contact the company but I doubt that it will do you any good. They will tell you to purchase another copy. Trading serial keys is illegal, so no one will give you one. Sorry try not to lose you serial keys anymore. put them in a safe place so you know where they are.