It seems that after issuing this command, you lose your license and the device can NOT be associated with new mikrotik account (with neither trial nor paid license).
The CHR router is basically stuck forever in free mode.
Am I missing how this command may be useful? Seems like a dangerous tool without any purpose to me.
The ID of each device is unique if you want for some purpose to change it you can do it
and to link the device with a new license you can go to your Mikrotik account and use that ID to get a license
that is for router boards
that is helpfull if you have an old mikrotik router with a license and you want to move its license to a new one without buying a license or if you want to move it to a 86× virtual router on a server or pc or whatever.