How to find your Product Key for Software you installed

We have all done it, purchased software, installed it and threw the DVD case in the corner of the closet.  Months later you want to reinstall that software on another computer and you cannot find the Product key, what do you do?  If you can't find your product key, but the software is installed, try Magical Jelly Bean Keyfinder, which can locate the keys for Windows and many installed programs that have Product Keys.  Once installed, you simply run it.  It will present a list of programs installed on your computer and the corresponding CD key, along with other information that typically is not necessary to write down.  Yes, it's free for the basic version that can scan for 300 hundred different programs.