So here is the problem: If you purchase music from you phone, how do you get it loaded up in google music so you can access it from all your devices? There really isn't a simple way to do it, but I have come up with what I think is the easiest way.
1st you need to download sync toy 2.1 from Microsoft's website. This will allow you to sync folders from your phone to a folder on your computer easily.
Here is where you can download sync toy 2.1
Download details: SyncToy 2.1
The next step is to plug your phone into your computer via USB and make sure it is set up as mass storage.
You then need to find the folder on your phone (via your computer) where your downloaded music goes.
Now you go back to sync toy, run it and create a new sync. On the left side folder you want to select the folder on your phone where your downloaded music goes. On the right side folder you want to select the folder on your computer that you want google music to scan for new music.
After selecting the folders your going to be taken to a menu where you can select what kind of sync you want to do with this pair. I selected contribute. This allows me to delete songs from my phone after I sync but they will stay in the folder on my computer. This way, as I download more songs and add them to my library on the computer, I can delete them from my phone to save space.
Next you name your sync. Something like "Amazon MP3 phone to PC".
Now you run the sync and everything in the folder on your phone will be on a folder on your PC.
Next you need to go to the google music manager on your PC.
Now you need to make sure that the folder your music is going to is being scanned by the music manager.
Be sure you have selected Other folders in the menu "select music to add to your music library"
You then want to "add folder" and select the folder on your computer that you previously selected in sync toy for your music to sync to (the folder on your computer, not your phone).
Now that you have created a sync and named it, the rest is very easy and only takes seconds. From here on, you won't have to repeat the steps above.
Now when you want to add your music from your phone to google music, you need to plug your phone into your computer, run sync toy, select the name of the sync, and then run. Your music on your phone will then be added to your folder on your computer and google music will automatically add it to your google music library. Once you have this set up, it just takes a few seconds to sync your music.
Even though the music is transferred to your computer quickly, I found it takes about 20 minutes before it shows up in my google music library.
I know it's not a perfect system, but I thought it might be helpful for some