Log into your server via SSH using a client such as PuTTY
Execute the command /usr/local/cpanel/cpkeyclt
Refresh your browser or log out and back into your WHM panel
Confirm that the message has cleared
If the license is not renewed, the issue may be related to your main IP address being different than the one originally licensed or some other issue that would require support intervention.
If the command above does not resolve the issue for you, or you cannot access your server via shell, please feel free to contact support via live chat or a ticket so we can assist you with getting this resolved.