Client made payment using PayPal but invoice not marked paid?

You need to activate Instant Payment Notification (IPN)

How to setup PayPal IPN? For PayPal invoices to be automatically marked paid when you receive a payment you need to enable IPN inside your PayPal account.

  • Navigate to Profile > Profile and Settings > My Selling Tools > Instant Payment Notifications
  • Click the Choose IPN Settings button
  • Enter in your WHMCS System URL eg. https://www.yourdomain.com/whmcspath/
  • Select the Enabled option
  • Click Save