[vkou]

Typically, every year, or every X years, you undergo an audit, that verifies that your processes are still compliant.

Yes, the edge case of "Fire everyone and hire some other people" does not trigger re-licensing. Also, hardly anybody does this, in order to do anything other then downgrade employees to contractors, or union-bust. That's because 99% of the time, companies, even with a lot of turnover, don't change their business processes out of the blue.

99% of the time, when they are being acquired for their licenses, they do.