There are a million ways to track your licenses, but I really like having a single app that keeps it all in one place, dedicated to only that. A useful feature for me is that you can store other docs along with the license. These could be PDF files sent with your license (startly software sent their license out like this to me) or emails. This way I get to keep a copy of the original email or other docs which often has useful info. I know I can do that in other ways, but by using LicenseKeeper it encourages you to actually do it because it's all built in.

One great feature is that it attempts to parse email for the serial number, developer info and developers website. The cast majority of times it has pulled all that info correctly. I don't know if I'll need all that, but seeing as it's so simple it's nice to know it's all archived. Now if I buy a software (meh, I buy a lot!) I just run it thorough here, takes 15 seconds.