Selling software online?

Ok so basically I have an desktop application that I want to sell to the world 30days at a time... Whats the best eCommerce plugin to sell license keys and manage everything? What web framework should I use? What have you guys used in the past? Is there any open source solutions? So far the only thing I've found is easy digital downloads with software licensing plugin for WordPress is there a better faster way of doing this? I would also like to have an affiliate program to make all you guys money too!!