The card you got was probably for a free month of Napster To Go.
Basically what Napster To Go lets you do is download as much music as you want, and transfer it to a compatible MP3 player. The Zen Micro works with Napster To Go.
The catch is that once you've stopped paying a monthly subscription fee of about $15, none of the music you've downloaded can play anymore. With Napster To Go, you're essentially "renting" your songs, and as long as you keep paying that $15/month, you can continue downloading to your heart's content.
Once you stop paying, the licenses for your songs expire.
You have to synchronize your player with your Napster subscription regularly so that the songs on your player get their license updated.
I've used Napster To Go with my iRiver H10, and it's a pretty decent service. At $15/month, it's quite expensive considering that another subscription service--Yahoo! Music Unlimited (which also works with your Zen Micro) is just $7/month.
<a href="http://music.yahoo.com/unlimited/">music.yahoo.com/unlimited/</a>
I am looking at downloading a program to mass music on my new zen micro. What program is the best for this? I got a free month of napster with the purchase of my zen micro, but I am not sure about downloading music. I mean can I just use the free subscription and download all my music for free and then cancel my subscription? Or do I have to have it for so many months? Any advice would be appreciated.

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