Hmm, never had to sign in to read on a Nook app on Android (other than when it was first being set up) that's strange. I just tested it again on my Nexus 7 with WiFi turned off with a few already downloaded books and they worked fine.
You can either use the Nook4PC software to download books or download them straight from your Nook library on their website. The first time you try and open one of their DRM'd books with a third party ePub reader you'll be prompted to enter your CC# and Name and that should allow you to open the book and read.
|