Looking for paypal solution for digitial goods

I have been trying to get a paypal integration working for selling digital goods, in this case software that will have a license key that I can generate after the transaction is completed.

I started with paypal express checkout wizard, but that hung at the end of the transaction without returning to my website. I found lots of questions on various sites from people with the same problem, but no solution.

I then tried a number of plugins, also unsuccessfully. They either fail on the paypal transaction, or have such paltry documentation that one has to start reading the php to figure out how to handle the return to do the digital download.

Has anyone out there found something that works fairly well?

Thanks