A change with your billing and subscription takes place if you bought the product during its promotional period. In your case, I'm assuming the period where you can use QuickBooks with a discounted subscription has ended.
With this, I'd recommend contacting our Customer Care Support. With their tools, one of our specialists can pull up your account on file and discuss how your account subscription is billed. To do so:
Go to Help.
Enter Billing and Subscription Increase in the What can we help you with? field.
Choose a channel where you wish to connect to our dedicated support.
Did you open the account a few months ago? Your discounted rate might be ended. You may open a new blank QBO account and migrate data from the old account if required. They offer a huge discount currently.