Artemis, the calm web reader, is thoughtfully designed to be both efficient and privacy-preserving. For instance, it logs only the last month you used it:

This is why “approximately” is something of a feature: I don’t know what day a user opened their feed last on. I don’t need to in order to fulfill my goal of not retrieving feeds for users who haven’t been active for a while. Not only that, I don’t want to know the last day a user logged in to Artemis, for that would mean I would have the necessary telemetry to easily calculate “daily active users” and such.

— James G, Designing for inactive users