In WHMCS, the "Sync Next Due Date" feature allows you to synchronize the next due date of a domain with your registrar. This ensures that WHMCS accurately reflects when a domain is set to expire based on information from the registrar.

Here's how you can enable the "Sync Next Due Date" feature 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. Domain Registrars: Under the "System Settings" section, click on "Domain Registrars."

4. Edit Registrar Settings: Find the registrar for which you want to enable the "Sync Next Due Date" feature and click on the "Edit" icon (pencil icon) next to it.

5. Sync Settings Tab: In the registrar settings, look for a tab or section related to domain synchronization. This can vary depending on the registrar.

   • Registrar-Specific Settings: Each registrar may have different options for domain synchronization. Look for an option related to "Sync Next Due Date" or a similar term.

   • Sync Next Due Date Enabled: Check the box to enable the synchronization of the next due date for domains.

6. Save Changes: After enabling the "Sync Next Due Date" feature, click the "Save Changes" button to apply your modifications.

7. Repeat for Other Registrars (if needed): If you have multiple registrars, repeat the above steps for each one.

By enabling the "Sync Next Due Date" feature, WHMCS will retrieve and update the next due date information from the registrar. This helps ensure that your WHMCS system accurately reflects when a domain is set to expire based on the registrar's records.

Keep in mind that the availability and location of this feature may vary depending on the specific registrar you are using and the integration with WHMCS. Always refer to the documentation provided by your registrar for specific guidance on configuring domain synchronization settings.