For those who have purchased music from Amazon before they introduced their cloud services, I recommend auditing your music collection. I purchased some music back in 2010 that I noticed was not in the cloud and that I was being told I had to purchase it again. You can go into your account and click "your order", then click "digital orders." From there you can find all digital purchases you made. If you notice any music that has not automatically transferred to your Amazon music cloud contact, contact Amazon (preferably via online chat) and they can add the song to your cloud.