In WHMCS, domain registrations are recurring products. WHMCS can automate management of these renewals through your domain registrar.
WHMCS can send domain renewal notices to your customers before their domain's due date and additional reminders after the due date passes.
After most domains expire, they enter a grace period and then a redemption grace period. Renewal during these periods may incur fees.
Domain transfers move domain names from one registrar to another. Most of WHMCS's supported registrar modules can automate transfers.
Checking the IP address that domains in WHMCS point to allows you to easily identify clients that may no longer be using your service.