WHMCS allows you to configure reminders for free domain registrations or renewals. This ensures that your clients are notified about upcoming renewals even for domains they received for free. Here's how you can set up free domain reminders in WHMCS:

1. Log into WHMCS: Access your WHMCS admin panel using your username and password.

2. Navigate to Configuration: Click on the "Configuration" tab in the top navigation menu.

3. Automation Settings: Under the "System Settings" section, click on "Automation Settings."

4. Domain Renewal Notices: Scroll down to find the section labeled "Domain Renewal Notices."

5. Enable Domain Renewal Notices: Check the box to enable domain renewal notices.

6. Set Days Before Expiry: Enter the number of days before a domain's expiry date that you want WHMCS to start sending renewal notices to your clients.

   For example, if you set this to 30 days, WHMCS will start sending notifications one month before the domain's expiry date.

7. Include Free Domain Renewal Notices: Check the box labeled "Include free domain renewals in the upcoming domain renewal reminders".

   This option specifically addresses the issue of free domains. When enabled, WHMCS will send renewal notices even for domains that were provided for free.

8. Save Changes: After configuring the domain renewal notice settings, click the "Save Changes" button to apply your modifications.

9. Customize Email Templates (Optional): You can customize the email templates for domain renewal notices by going to "Configuration" > "System Settings" > "Emails." Look for the relevant template named something like "Domain Renewal Notice".

   Customize the subject and message of the email to suit your business style and preferences.

10. Test the Notifications: Before relying on the automated system, it's a good idea to perform a test run to ensure that domain renewal notices are being sent as expected.

By enabling free domain renewal notices in WHMCS, you can make sure that your clients are informed about upcoming renewals for domains they received for free, allowing them to take the necessary action in a timely manner. This can help prevent any disruptions in their services due to expired domains.