I've been tasked with setting up a platform for software distribution. Basically the user would log into the website and then have the ability to download software.

It would need the ability to allow for customization of what software each user can download based on what they have purchased or preferably has a current subscription. It would need the ability to support the download of a variety of software applications along with previous versions. Integration with an ecommerce site would be extra helpful.

I'd rather not go through the pains of developing a custom solution, so I'm looking for a potential COTS solution. Anybody have any leads on this?