3rd party app billing question.

Are 3rd party apps allowed to charge you for a renewal subscription service (ifit) without notifying you beforehand?? I signed up for a 1 year free subscription service that recently ended and they automatically charged me without notifying me beforehand. It may have been in the fine print when I signed up, but I was never notified that my service was automatically renewing during the free subscription service timeframe. Does apple have terms and conditions that requires these 3rd party apps to notify customers when they're subscriptions are renewing? And charged? Thank you for your time.