The managers of this hypothetical software company would surely complain if their cars were remotely disabled because the manufacturer wanted to sell a new model. Similarly their customers should complain (via the courts) when the product they bought is remotely disabled to force them to upgrade.

As a sibling poster points out, running a license server is a trivial expense and if you require it for your product you should budget to keep it running. It's roughly $400 for a perpetuity paying $20/y to run the server indefinitely.