If you used a trial license and want to continue with a full license, or you have any issues with the license, you must update the cPanel License Key.
To update the cPanel License Key:
1. Connect to your cPanel server SSH as root
2. Execute the command:
# /usr/local/cpanel/cpkeyclt
root@web [~]# /usr/local/cpanel/cpkeyclt
Updating cPanel license...Done. Update succeeded.
root@web [~]# To see the cPanel license log:
# cat /usr/local/cpanel/logs/license_logMon Nov 23 07:22:07 2020: License request made by process 22380 - -bash
Mon Nov 23 07:22:07 2020: License Update Request
Mon Nov 23 07:22:07 2020: Using full manual DNS resolution
Mon Nov 23 07:22:10 2020: Trying server 208.74.121.83
Mon Nov 23 07:22:10 2020: Connected using local address X.X.X.X
Mon Nov 23 07:22:11 2020: Server 208.74.121.83 on port 2089 returned:
Key Accepted
Key Follows
Mon Nov 23 07:22:11 2020: Obtained lock license file
Mon Nov 23 07:22:11 2020: Update openid connect client credentials
Mon Nov 23 07:22:11 2020: Accepted license from server 208.74.121.83 on port 2089
Mon Nov 23 07:22:11 2020: License update succeeded after trying 1 server
Mon Nov 23 07:22:11 2020: Scheduling cpsrvd restart for successful license refresh (graceful with autofallback to hard) 
very informative article.