All apps that are available on the Apple App Store are bound by Apples’ terms and conditions. Let’s go over these.
Apple’s terms state:
“Individuals acting on behalf of a commercial enterprise, governmental organization or educational institution (an “Enterprise”) may download and sync Apps for use by either (i) a single individual on one or more devices owned or controlled by an Enterprise; or (ii) multiple individuals on a single shared device owned or controlled by an Enterprise. For the sake of clarity, each device used serially or collectively by multiple users requires a separate license.”