If you try to access WHM/cPanel one day but are shown an error message stating “License File Expired,” first you can go to cPanel’s License Verification page and enter in the IP address that is attached to your cPanel license. If it shows as valid then you can run the following command under root:

/usr/local/cpanel/cpkeyclt.

If that does not work and the error still persists, you will need to open a support ticket with cPanel to have them look into the issue.