Edit: ok I found the difference on this page: https://www.amazon.com/gp/help/customer/display.html?ref_=dm... Basically if you don't push the button, they will delete your files. If you had a paid storage plan, they will keep your original files somewhere, but they won't be accessible from your music library. If you push the button, you can continue to play and download your music like normal, but you still can't upload any more.