When accessing cPanel OR WHM you see message which says cPanel license is not activated. There are 3 reasons behind it.
1. cPanel license not activated. Access verify.cpanel.net. Check if the license is activated on server IP. If is is not, you will have to opt for one.
2. cPanel license activated but not updated. If cPanel license is purchased, you will have to update it on the server as root via SSH. Execute the command /usr/local/cpanel/cpkeyclt
3. Firewall is not allowing to update the license. When connecting cPanel’s license server, it uses port 80. See to it that outgoing connection on port 80 are opened/enabled.
4. Server’s hostname is not a FQDN. cPanel servers require a Fully Qualified Domain Name to be set as the server hostname. Make sure it is set. Example of FQDN is server.yourmaindomain.com