Need a simple way to add an affiliate program to your WordPress site and connect it to your WP Simple Pay payment forms? We highly recommend (and use) AffiliateWP.
Simply create a payment form as usual, then head to this AffiliateWP doc for additional setup and help.
Note that recurring referrals are supported as long as you have their add-on for this installed.
Note: Subscription capabilities are included with a Plus or higher license only.