Occasionally cPanel on CentOS7 needs a bit of a nudge to refresh it's cPanel license, particularly after a reboot. You can log into your VPS via SSH and run the following command to give it a nudge:
Another tip is to add a job to root's crontab as follows:
@reboot echo /usr/local/cpanel/cpkeyclt | /bin/at now + 1 minutes > /dev/null 2>&1
This will automatically run the command 1 minute after a reboot and prevent the issue from recurring.