Starting from September 2014 there are New Terms of Use of JW.ORG.

Some features in the JW Bible Reader app seem to violate this new statement.

So starting from version 7.0 some publications won't be available for download (and you won't be able to install them in any way, even if you have a PDF file). Only those that have the EPUB file will be downloadable. If you have downloaded publications that do not have an EPUB file available in previous versions of the app, then don't worry: these publications won't be uninstalled and will remain in your app.

Will the app be removed from the Windows Store?

No. I will continue developing and improving the JW Bible Reader app. I will do all I can for the app to meet the new terms of use.