https://docs.whmcs.com/8-0-9/tags/addon-modules/
addon-modules - WHMCS
addon moduleswhmcs
https://docs.whmcs.com/8-11/tags/addon-modules/page/2/
addon-modules - WHMCS
addon moduleswhmcs
https://docs.whmcs.com/8-12/tags/addon-modules/
addon-modules - WHMCS
addon moduleswhmcs