GPM is split into two sort of services. Uploading 20k songs, song matching, access to your uploaded library via phone/web browser is all free period. The 'All Access' portion is what you pay for. It gives you access to music you don't already own. Basically all the music on Googles service, so when an Album comes out you can just listen to it all you want instead of having to buy it, so long as you pay a subscription fee. But even if you cancel all access, you still can have up to 20k songs uploaded from your personal music collection accessible.