The way that this automatic renew thing is hidden is disgusting.
There is an account page on Avast's site with licenses and their details. THIS is where the options should be stored.
Expecting a customer to dig up a year old email because they were automatically opted into an auto-renewal process is just not customer friendly.
This is either incompetence in the usability department or an actual attempt to obfuscate the auto-renewal management in to make it difficult to leave.
Whatever the truth it doesn't look good for the company.
Autorenewal information along with correct URL and Order ID, plus password is sent to customers 30, 15, and 7 days prior to renewal. All the information is specified in that email to cancel auto renewal.
The original order confirmation "from 1 year ago" also contains the same information regarding auto renewal.
As Eddy mentioned, auto-renewal can also be disabled at the ordering stage, before you even enter your personal details and credit card information.
Furthermore, the auto renewal reminder also contains the exact date billing will take place, which is typically 5 days before the expiration of the license.
We're simply asking users to help us, help you.