I‘m a former polar researcher converted into a developer. Some years ago, I was working for a popular Mac reference management app. When subscriptions were added, I was arguing heavily to have relaxed rules of license enforcement, precisely for cases like described in this thread. But unfortunately, it was considered an edge case back then.
In all academic disciplines which rely on field research, elongated field trips with no or only sparse internet access aren’t uncommon. When I was on a 2.5 month research expedition to Antarctica, there was no internet access (except sending emails w/o attachments via the ship’s satellite connection which you had to pay for). What makes things worse, these field trips are also very important times for researchers to work on their data and academic papers. I.e., they definitely require their apps to work reliably during this time.
For these reasons, I’ve personally decided to prefer native apps that are payed with a one-off license and which don’t rely on a web service in order to function properly. For the same reasons, I’ve decided to always offer one-off licenses for the app that I’m developing (which targets academic customers).