Problem is the long tail user retention story is incredibly bleak on mobile. It's considered an achievement to get them to last a week, never mind a month.
That sounds like the "free trial" system working. Someone looking for an app for X purpose installs 10 of them and deletes all but one - giving very low average metrics.
It's more like the "one" they keep is also free, and marginally less useful or slightly more irritating to use.
Mobile app stores are a cesspool of terrible ideas and naive people who think if only they give away their time developing free software some company will notice and bless them with a job. The few gems to be found are a stark contrast.