My guess would be that the app contains some log-in information or a key to verify access to the actual content which is stored on the vendor’s server, not your local device. So, yeah, it’s an anti-copy measure. It’s a constant battle between authors and copyright-infringers and, like always, it’s the honest reader that pays the price.
Self taught, persistently behind the times, never up to date. AKA ~ jeff
More verbosity: http://petiteguerre.blogspot.com/