When you purchase a Nexus 6, Google will add in six free months of Play Music All Access. The device was briefly put up for pre-order earlier this morning, but quickly went out of stock. As of now, the shopping page merely says there's no stock, and suggests folks check back soon. There's no indication when stock will return, however, and it's unclear how many units were available in the first place.
If you did manage to snag a unit, you have until Jan. 31 to redeem the offer; you also need to purchase the device by Dec. 31, 2014. Additionally, if you've subscribed to All Access in the past 12 months, you're not eligible for the promotion. There are some other terms, which you can see at the link down below.
Google just recently updated its Music experience with some Songza love, promising better curation and discovery. It also got infused with some nice Material Design, making it more consistent with Google's brighter look and feel on mobile. The service goes for $9.99 per month, which means you'll save quite a bit during that six month trial. As far as streaming music services go, Google's is pretty great, and offers up a good fight as an alternative to something like Spotify.