For LISTEN Free content (or LISTEN Sponsored content for Freemium users), no credits are needed at all. Just enjoy hundreds of free songs!
You can add other LISTEN content for 2 credits per song--including Music, Status, and even Curated Jukebox. If you already have credits in your account, just find the content you want and click Buy.
To purchase credits in the app, click Menu > Accounts > Get More and select the number of credits you want to buy. The options are:
4 Credits = $3.99
10 Credits = $7.99
20 Credits = $14.99