PyXLL is licensed on a per-user basis, not per machine.
If you want to use PyXLL on multiple PCs for your own use (for example, a work PC and a home laptop) then that is no problem at all. You would not require a second PyXLL license in order to do this, the same license key can be used on both PCs.
If you have a team of users, then you will need to ensure that you have a license key for the number of users you have, but any of those users may use PyXLL on multiple PCs.
If you have any questions regarding licensing, please contact us and we will be happy to help.