In the event that your cPanel license gets out of sync with cPanel's server, you may have an invalid error when you attempt to login to WHM or cPanel. To fix this, you can login to shell as root and execute the following command:
The result should be:
Updating cPanel license...Done. Update succeeded.
Building global cache for cpanel...Done
If you have continued problems, please open up a support ticket at https://portal.my-tss.com/clientarea.php