Where is the activation key for Miss Management stored on my computer?

My husband needs to format our computer tonight to install Windows 7. I bought Miss Management from Yahoo Games a while back. I moved the game folder to our external hard drive (and it still plays) but my husband pointed out that the game works because of an activation key and if the activation key hasn’t been moved, it’ll get deleted when he formats. I can’t find ANYthing on Yahoo’s site about downloading games you’ve already purchased, or where the activation key is, or how to get another activation key if you lose one that you already paid for. HELP!