shopiing carts

Hello everybody, I was wondering if you guys can recommend a good shopping cart?
The challenge is that the product we are putting int he market place soon is an .exe file for the forex market, however to avoid the slaughtering from Jack Sparrow (piracy :P) we have implemented a way to allow 2 copies per account and they will get a code that it will be specific to their copies, so we need a payment system that can give them those codes once they pay.
Anybody has an idea of where to go?

Also if anybody is in the forex market we'll be posing the JV proposal soon, but this is not the topic to do it, however if you are interested IM me please.

Thanks ya'l

Not sure if this suits, but thought i would throw it out there. What if you made the code something they already have, which is unique... like thier email address, or CC number?