NO reselling anything made by anyone else is allowed on free hosted WordPress.com blogs.
WordPress.com blogs cannot be equipped for ecommerce transactions with shopping carts and no blogger initiated advertising or paid or sponsored content is allowed. The only things you can sell on WP.com blogs are products that you, yourself create and/or services that you personally provide. For an online store with a shopping cart you need an independently hosted blog using WordPress.ORG software. http://wordpress.org