To transfer or move a license, uninstall CSS HTML Validator from the old computer and re-install it on the new computer. You will have to re-enter your registration information on the new computer.
If you want to keep your old options and settings and not "start fresh" with the default options, then see the Backup Options topic for help with restoring your options on the new computer.
If you don't have your registration information or license key then you may be able to have it emailed to you from the CSS HTML Validator website. You may also be able to re-download the CSS HTML Validator setup program.