Licenses are issued to the company (if the company name is specified in the order), so they are not bound to any individual name.
If a user leaves the company, you can unlink the license ticket from the user record. If the user doesn't or we don't do this, then the new user will not be able to link the license ticket to the corresponding user record, so the user won't be able to access the license information via the My Control Center section of the support site.