CIA Professional Chef app not supported

Last year I purchased the Culinary Institute of America’s ”Professional Chef” app (not an iBook but this seemed to be the closest community to addressing my issue). It’s interactive e-book of the text they use at their school. It is not supported in iOS 11 and has been pulled from the app store. Very disappointing given this app cost $50. I read that the license might be used with the inkling app but didn’t see it on that app. Anyone know if this content is assessable anywhere else under the $50 license already purchased? If not do I have any recourse against developer? Thanks.