This document explains how to add coupons / promotion codes for your extensions on ExtensionPay.com. You should already have ExtPay installed in your extension and a connected Stripe account set up through ExtensionPay.
Stripe allows creation and management of coupons and promotion codes on this page in your Stripe settings.
In Stripe, a "coupon" is an object that when applied to a purchase can create a discount. Coupons can have associated "promotion codes" which is the actual short alphanumeric string a user enters when paying in order to apply the coupon discount.
To create a coupon, use the Stripe coupon creation form, pictured here:
You can use any settings you want for the discount, but the important part is to turn on the option labeled "Use customer-facing coupon codes". This will allow you to create a promotion code you can give out to customers.
To apply a coupon during payment for your extension, customers will just need to click the "add promotion code" button shown below on the Stripe Checkout page:
