I have seen this in one other topic, the cancellation has been confirmed, but the information in the Registration information (from the Avast tray icon), still shows your existing information.
Now that other topic had a response on that issue. From memory I think it was that the subscription is still valid for the remaining period up to the (previous) renewal date.
But my guess (as an avast user) is that it would be fairly hard/complex to change this within your installed program and reflect the two different things, the date the subscription is still valid for and that the auto renewal has been cancelled.