You have until December 31st of 2012 to install the Box app and sign in to take advantage of the offer. Once set up, you will get to keep all that extra storage for the rest of your life. Being that the Nexus 4 lacks in physical storage, this isn’t all that bad of a deal.
If you already have Box account and haven’t signed in through your new Nexus 4 yet, you should probably do that soon to make sure you get the storage. Unless of course you already picked up the extra space through a previous promotion. Feel free to snag the Box app below by simply clicking or scanning the QR code below. Enjoy your extra free storage.