Stripe is an online payment processing service, like PayPal, only with better rates and without all the branding. Stripe allows you to securely process payments as well as setup and manage subscriptions. Stripe’s payment method allows your application to know the moment a payment is submitted, whether or not it is valid, and there is no pending period (unlike PayPal).
Contained, is the web edition and desktop demo applications, with full un-encrypted source code, so you can extend and change any Stripe APIs you desire.
You may not resell the source-code, but may use it unlimited/repeatedly in your own applications.