MU paid/ free subscription, allow file downloads via fee shop cart?

Some users will post their content available for free look on site and some content will go to library for paid download via shopping cart. Down load doc/ pdf, zip file, for extraction on home box, for use on home box. Subscribers will comprise both free subscribers and paid subscribers. The paid subscribers will be the ones uploading files. Will WP allow this and what plugins might I review? It would be file uploading to library, then file download from library via fee based shopping cart.
Thanks in adv for any advice.