Thanks for clarifying my murky comment. Also, with Prime you can listen to lots of full length tracks, but often if you ask Alexa to play a certain song it says and plays, "here is a sample" of that song.
I have had a music download service for 10 years. It recently created a free cloud of all the music I have downloaded over the years. I have installed the app to go with it. With app, I can listen to any of it on phone, turn on BT, and bingo, the Echo is now playing it through its speakers. There are lots of ways to hear one's own music on the Echo other than via Amazon.