League License is designed to help you sell products on your own website and, as of the time this article was written, you can add NFL, NCAA, NBA, NHL and MLS products to your own website as long as you do not also sell unlicensed or fraudulent or counterfeit products on your website. Visit http://www.leaguelicense.com/seller-participation-agreement.html for more information. At the time of this article, you need approval from MLB to sell MLB products anywhere online.
Can I sell other league products on my website that are not available in League License? As far as other league products are concerned, you will need to refer to your licensing agreements with the leagues regarding those products.
Can I sell League License products on third party websites like Amazon or eBay? At the time of this article, you can also sell NCAA, NBA, NHL and MLS products on third party websites. For some third party websites, you need approval from the manufacturers of those products before you list their NCAA, NBA, NHL and MLS products. At the time of this article you cannot sell NFL or MLB products on third party websites.