Barnes and Noble has just removed the ability to download eBooks that you have bought from the online Nook Store. They did this so users could not download purchased content locally on their PC and either strip it of the encryption or use a 3rd party reading app.
The Barnes and Noble customer care division has sent out a tweet, letting people know that this is their new policy and not a bug. “The ability to sideload NOOK purchased content has been discontinued. We apologize for any inconvenience this may cause.”
If you own a Nook e-reader or tablet, you will continue to enjoy purchasing and reading books right on your device. Ditto for people who use the official Nook app for Windows, Android or iOS. This issue mainly affects people who use an internet web-browser and accesses their Nook Library. In the past, a download option would appear, but now this has been removed.
There are some rare cases where select eBook titles still have the download button, but include the text “We’re working on making this title available on NOOK for Web. In the meantime, read it on our free NOOK Reading Apps.” I also confirmed that graphic novels still have the download button, because they are currently incompatible with the Nook for Web HTML5 based e-reading app.
The elimination of downloading titles to your PC will mainly effect the “power users” that tend to use 3rd party e-reading apps for their mobile devices or strip the DRM completely and bypass Nook security.
Barnes and Noble is currently in the process of totally revising their website for purchasing content and also the way Nook books are presented. In early 2015 it will be formally unveiled and likely this change to downloading content is likely a precursor to reading everything exclusively online.