Problem with subscriptions renewal dates.

I have a problem with subscriptions and does anyone have a solution or reason why this is happening? As an example my subscription renewal date(which is monthly) is different from my billing date for Audible it was paid on the 27th of December but the renewal date is the 16th of January so I cancelled my subscription to see what happens on the 16th. I’ve included some screenshots to show you what I’m talking about.