NShape Sets is simply a tool to help you execute your workout routine and close your rings.
No login - Just set how many sets you want to do and how much rest you need.
Rest is over - NShape Sets will let you know when its time to get moving again. Well never send a promotional notification to you.
Your data is yours - No data is being collected. Ever. HealthKit access is only needed if you want to log your workouts to the Health app.