I'd have thought that it wouldn't be significantly different to crack the in-app content and provide that for free as well, or even repackaged into the original

I'd have thought that it wouldn't be significantly different to crack the in-app content and provide that for free as well, or even repackaged into the original app. About the only thing that I can think that will defend against this is a streaming/always online service that actively requires cooperation from a server as part of its implementation. Any offline licensing system can and most likely will be cracked eventually, until you end up with the equivalent of CD-keys and server-side detection of duplicates or invalid ones. Even then, if you're only using the remote end for license validation, that code can just be removed - the most viable models are either streaming content (in a way that can't be batched and rehosted/provided locally), or offering compelling multi-player / shared online features that require a valid auth token.