These are some payment webpages I built for a desktop app. There is a free version of the desktop app. When the user wants access to the full version of the desktop app they can click a link in the app that will take them to the payment webpages. The payment pages allow the user to purchase a limited or full version of the desktop app and they can upgrade from limited to full. There is also a promo code CMS so that the owners of the app can create promo codes for limited, full and upgrade.