Just reinstall from time to time.I do both, activating and evaluating.
Totally irrelevant if the machine is virtual or physical. No rocket science: one license, one machine. When a license (product key) is used on any physical or virtual machine to activate Windows, it is no longer valid for activation on any other physical or virtual machine. Same rules apply to virtual machines as to physical machines. If you want to / need to run let's say two activated Windows 10 virtual machines on one host physical machine, you will need three licenses: one for the host and one for each virtual machine. One license is valid for one installation, if that installation is physical or virtual is completely irrelevant. It is really simple: to activate Windows on any physical or virtual machine you need a valid license (product key). The host machine license and activation status has nothing to do with virtual machine, nor has license and activation status of any other virtual machine. You can use it without activation with limited functions (for instance no personalisation) for a short period of time, or you need to activate it with a valid license. Regarding Windows license, a virtual machine is as any physical machine.
