I think the main thing that causes that is the MAC of the Ethernet NIC. If you "move" it, the MAC stays the same. If you "copy" it a new MAC is generated. Usually resulting in re-activation requirement. When you move and keep the MAC, you can't network both copies at the same time as there will be 2 identical MAC's and that won't work. "Move" is good when you do it for backup.
Now is not the time to dream and drift, there's work to do and loads to lift. ¯\_(ツ)_/¯
The key difference between the "I moved it" and "I copied it" is with the "I moved it" , the Universal Unique ID (UUID) of the VM is kept the same.
For a Windows OS licence that require activation, having a different UUID would likely mean reactivation of the licence or re-key of the Windows licence key would be required as the installed OS inside the VM sees it as "new hardware" (i.e. it as if OS licence key is applied to a different machine).
Other software might also depend on UUID for licencing or some combination of other unique parameters such as Ethernet MAC address.
The UUID of the VM is in the vmx configuration file of the VM.
uuid.bios = "some 32 hexadecimal digit string"
Thanks for the response. Yes, as with a Copy I get a Windows Activation request. Now I know it's the MAC.
Thanks for explaining that it is the UUID. Even better, thanks for letting me know where uuid.bios is recorded!