The plugin integrates J2Commerce with the 2Checkout payment gateway. 2Checkout allows you to accept payments securely from customers

Trusted by over 50,000 merchants, 2Checkout supports transactions in 196 countries through 8 payment methods, 26 currencies, and 15 languages, forming one of the leading processors of online transactions in the world. The service is simple to implement, including a pre-integrated payment gateway, a merchant account, PCI compliance and international fraud prevention

It comes with a documentation PDF which can be downloaded after purchasing the plugin in your My Downloads area