How to transfer Plesk license to a different server?
A Plesk license can be used on a single server only. That is why if a license should be transferred to a new server, the old server has to be closed, or re-activated with the different license.
In order to transfer the license to a different server, just re-activate the new server using the same license in Tools and Settings > License Management > Install key
Note: the same license can be used on a server that was re-installed from scratch.