Prime members have free access to over a million songs through Prime Music. Amazon Music Unlimited, which is separate, is the company's premium service, and it's designed to be a rival to Spotify and Apple Music. It's currently available in over 35 countries worldwide.

While Amazon Music Unlimited may not have the subscriber numbers of competitors Apple Music of Spotify, it does have the brand power of Amazon behind it. People who listen to music on their Echo devices might be sorely tempted to upgrade from Prime's free music selection, especially considering the company recently updated its line of speakers (and introduced many new products as well).

Update, September 26thm 12:10 PM ET: This article was updated to reflect pricing and availability of the Unlimited service.