Hello.
If you have already used the product key to activate Windows on the previous virtual machine, you may not be able to use the same key to activate Windows on a new virtual machine.
This is because the product key can only be used on one machine. The prerequisite for moving the product key is that you need to deactivate the product key on the previous machine. You can do this by opening the Command Prompt as an administrator and running the command "slmgr /upk". This will uninstall the product key from the old virtual machine.
Once you have deactivated the license on the old virtual machine, you can activate it on the new one by going to Settings > Update & Security > Activation and entering the product key.
Best Regards,
Hania Lian