Starting from the 1st of December 2020, resellers are able to allow or disallow to use CL6 ELS repositories for each IP based license and Subaccount. When this option is allowed, a system with CloudLinux OS 6 can be activated with such license.
At the end of the month CloudLinux billing will calculate how many servers running on CloudLinux OS version 6 along with versions 7 or higher. The price for CloudLinux OS version 6 will be different. See detailed pricing here. By default, if on the 1st of December 2020 you had CloudLinux OS version 6 running on your servers, then for each such IP based license or Sub-account this option will be enabled.