it is a 30 days thing... if you paid a subscription (apple and google has them), it will automatically renew after 30 days.
If you paid using any other platform, it doesn't charge automatically, you have to hit the button again after 30 days.
Or if you used the "1 month" payment, it only charged for 1 month, no subscription. So after the month is up, you have to do it again manually.