We cannot access metadtat on free hosted WordPress.com blogs.
Please read this > http://en.support.wordpress.com/affiliate-links/
There is only one advertising program called WordAds at WordPress.com. It’s for blogs on their own domains. This is the homepage for the WordAds program: WordAds.co. 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
the only exceptions are in italics:
Affiliate marketing blogs: Blogs with the primary purpose of driving traffic to affiliate programs and get-rich-quick schemes (“Make six figures from home!!”, “20 easy steps to top profits!!”, etc). This includes multi-level marketing (MLM) blogs and pyramid schemes. To be clear, people writing their own original book, movie or game reviews and linking them to Amazon, or people linking to their own products on Etsy do NOT fall into this category. Here is a thread in the support forums that talks more about which affiliate links are OK or not OK. http://en.wordpress.com/types-of-blogs/
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/