If you're asking yourself what Milk Music is, you're not alone. Samsung bought the Milk Music service in 2014 to be offered exclusively on its own devices. However, since then the music streaming industry has seen increased competition with big players including Spotify, Apple Music, Pandora, and Tidal owning the market. That's why it's no surprise Samsung will be "sun setting" Milk Music in the United States on September 22, 2016, as the company announced in a blog post:
We have made the strategic decision to invest in a partner model focused on seamlessly integrating the best music services available today into our family of Galaxy devices. We believe that working with partners will accelerate innovation, enhance device sales, and provide amazing new experiences for our customers.
If you can't beat 'em, partner with 'em.