WordPress.com free hosted blogs are provided for blogging and not for flogging merchandise that we bloggers don't create ourselves. Our blogs cannot be equipped for eCommerce. The software will continue to strip the affiliate links out. We are not allowed to set up Amazon stores on free hosted WordPress.com blogs. You will have to switch to paid hosting and a WordPress.org blog if and Amazon store is what you want.
There is only one advertising program called WordAds at WordPress.com and it’s for blogs on their own domains. This is the homepage for the WordAds program: http://www.wordads.co/ There you will find the application page as well as FAQs.
Aside from a blog being accepted into WordAds, no blogger initiated advertising, retailing or reselling the work or products created or services provided by anyone other than yourself is allowed on free hosted wordpress.com blogs. E-commerce transactions via shopping carts and the like cannot be conducted on free blogs from and being free hosted by wordpress.com
If you do require an ecommerce site, advertising and/or affiliate links you can hire a web host and get a free software install from http://wordpress.org Refer to > http://support.wordpress.com/com-vs-org/