Books purchased from B & N are copy protected with "social DRM", this is tied to both your Adobe account and the credit card you paid for the book with. B & N figures you might be willing to share your Adobe log in with others, but not your credit card info. In effect this keeps any other device from being able to read them, even Adobe reader cannot open them. You can read on your nook, or the software for your computer. A few of the free books will transfer, but you can get those almost anywhere. I personally refuse to buy from B & N until they change that; if I paid for it I should be able to use it on any device, within the limits of the DRM laws.