WHMCS allows you to configure renewal notices to remind your clients about upcoming renewals for services like hosting, domains, and other products. Here's how you can set up renewal notices 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. Product/Service Renewal Notices: Scroll down to find the section labeled "Product/Service Renewal Notices."

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

6. Set Days Before Expiry: Enter the number of days before a product/service'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 product/service's expiry date.

7. Configure Additional Options (Optional): Depending on your preferences, you may find other options related to renewal notices that you can configure, such as "Send Reminder for Due Service Addons" or "Send Notice on Manual Renewal".

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

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

   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 renewal notices are being sent as expected.

By enabling renewal notices in WHMCS, you can help ensure that your clients are aware of upcoming renewals for their services, giving them the opportunity to renew in a timely manner. This can help prevent any disruptions in their services due to expired products or services.