Music that free subscribers uploaded will still be available for streaming and downloading until January 2019. Paid subscribers will retain access to their music (until then) as long as they don't let their membership lapse. If they do, there won't be any way to re-start, and only 250 of the uploads will remain stored for free for a year. Basically, you're out of luck if you have more than 250 songs uploaded to Amazon. You can still upload 50,000 songs to Google Play Music for free, (or twice as many songs if you use a Samsung Galaxy S8), though honestly who does that anymore?