How do I turn off the automatic renewal on my subscriptions?

Don’t think I should have to cancel my subscriptions every month because of that I have had iPhones since the iPhone 4 and here lately I have been thinking about switching to android because of this and a few other issues I have been having with my iPhone

I don’t want to cancel the subscription just don’t want them to take the money off my card every month without me telling them they can

OK thanks everyone