The subscription to Apple TV+ is offered with a free year for a new purchase. But users still have to redeem that offer, and sign up. It is not automatic.
When you signed up for Apple TV+, then you would have received an email message with full details for the subscription, including duration of the free trial period, and the first due day for subscription fees. Please verify that.
Verify your Apple TV+ subscription in your subscriptions overview. It will list the Next billing date on the grouped page. On the subscription details page, it will list “Free for 1 year” if applicable, and the Renewal date (same as next billing date) - which should be a year from when you signed up.
If you canceled and resubscribed, then you would pay from the resubscribe moment.
If you ordered anything that is not part of the subscription, then that would be payed for separately.
E.g. items with a Buy or Rent price would be from the iTunes Store, and that is not included with Apple TV+.
See your purchase history for the App Store, iTunes Store, and more - Apple Support