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.
Once you have AffiliateWP installed and activated, simply create a payment form as usual, then follow along in this AffiliateWP doc for additional setup and help.
If you have the optional AffiliateWP Recurring Referrals add-on installed and activated, you can follow this AffiliateWP doc to set that up as well.
Note: Subscription capabilities are included with a Plus or higher license.