Yes, 禅眠-科学睡眠管理APP is completely free and it doesn't have any in-app purchases or subscriptions.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
禅眠-科学睡眠管理APP is free.
To get estimated revenue of 禅眠-科学睡眠管理APP app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.