Code Shop v2.1.0 is a powerful widget, which allows you to sell
coupon/voucher/license codes directly on your website (even if it is
plain HTML-website). This PHP Script will handles payments through
multiple payment gateways (PayPal, Payza/AlertPay, Skrill/Moneybookers,
Authorize.Net, InterKassa, Perfect Money, BitPay and Stripe) and can be
easily integrated into any webpage (no more difficult than insert
Facebook Like button, check out steps 5-6 in “Installation” paragraph).