iPhone What constitutes a month-long subscription? 30 days? 4 weeks? 31 days?

[SW3029]

When you subscribe to an in-app subscription plan for a month, how long is the "month"?

Is it four weeks?
Is it 30 days?
Is it 31 days?
Is it until the same day next month (For example, February 16–March 16)?

 

[sparksd]

My Luminos, National Geographic, Apple TV, AppleCare, and Apple News subscriptions each renew on the same day of the month.

 

[fwmireault]

Same for me, so I believe it’s the last option of the ones you listed