When you've cancelled your Premium Account after an automatic renewal you are still supposed to pay the subscription costs for this new billing cycle.
Every new billing cycle you're receiving all the perks of the Premium Account.
You are still expected to pay the costs that come with that.
Where can you cancel your subscription
You can cancel your subscription any moment on the 'My Premium Account' page, but you need to cancel it yourself.
When you cancel, you'll get a confirmation email.
Of course, after you've cancelled you can still avail of the services of the Premium Account until the last day of the current billing cycle.