I was hired in the early 90's by a collection of franchises for a home care company. The privately owned head office self-developed and distributed required monthly updates to the only software franchises were permitted to run their business. The monthly updates (floppies) reset the license for another month at each location. After years of problems, poor support, and in a couple cases offices getting shut down because head office just "didn't like them anymore", they banded together to sue the owners (one of which developed the software). I did IT work for a couple of the offices and was already familiar with maintaining the software / systems. They hired me to bypass the licensing code which was a lot of fun to figure out. In the end I wrote a DOS based license generator each office had that could update their software by just getting a code over the phone for the upcoming month (or any date for 365 days). A few years later once the lawsuit settled and the company broke apart we issued a patch for the software to remove the license check completely. I should fire up DOSBox sometime so I can play with that old software again.