The only app that does Adobe DRM is Txtr, but unless they've updated it it won't work with timed Adept DRM that is used for library books.
Overdrive announced months ago that they were coming out with their own reading apps, but no one has heard anything since the initial press release.
The only way to do it right now would be to strip the DRM and use an ePub reader (like iBooks) and then delete the book when you're done with it.
|