Our favourite Payment Processor is PayproGlobal.
They have outstanding Customer Service and an array of features that are perfect for many online businesses.
Memberpress is our goto Membership Plugin, so it made sense to combine the two.
PayproGlobal can handle all your payments and Memberpress will take care of the rest.
Install the Plugin in the normal way.
Remember to add the Product ID from PayproGlobal when you create your Membership in Memberpress.
Your Membership Set up should be the same as your product set up in PayproGlobal.