I've never come across the idea of a Software Kill Switch before and I hope I never do again - it really is appalling:
One vendor I deal with daily did exactly that to me this week. I had a fully legitimate copy of their software with all my dues paid and ducks in a row. But because I chose not to pay extra to get the newer version, which had been out for several months, they pulled the plug on me this week and won't let me use my legally purchased software unless I upgrade to the newest version. They say this is because the copy I'm using "is not the latest version."