by Cristián Lávaque » May 29th, 2011, 12:23 pm
Yeah, they're Pro only and they work with pro-forms (PayPal and Authorize.Net).
If you want a very basic implementation of the coupons, you could edit the shortcode amount value dynamically with PHP based on a coupon you pass to the page in the URL: example.com/page-with-button?coupon=50off
You'd have to have it custom coded, which would probably cost you as much or more than the Pro license, which has coupons and other added features.