You will need to upgrade to the latest version of Bookshelf by December 20, 2016.
This only affects Bookshelf apps that you have downloaded and installed on your device. If you only use Bookshelf in a browser, you do not need to do anything.
Please go visit this link and make sure you download and install the latest version of Bookshelf for your Mac, Windows, iOS, Android, Chromebook or Kindle device:
Make sure you are running one of these version of Bookshelf by December 20:
Bookshelf Windows 7.0
Bookshelf Mac 7.0
Bookshelf iPad / iPhone 3.9.2
Bookshelf Android / Chromebook / Kindle 3.9