This usually means the credentials were entered incorrectly. Remember that License Keys, Usernames, and Passwords are case-sensitive, and hyphens are necessary. A big "0" is the number zero, while a little "o" is the letter. If you continue to receive an error, you should use the official ESET license recovery page to resend your credentials and verify you are entering them correctly.
Enter the email address used when purchasing or registering the license. Submit: Click "Submit" or "Convert". eset convert license key to username and password free