Login to your account.
At the top of the page, click on ‘Domains’ and select ‘My Domains’ from the list of suggestions.
Click on the three dots beside the name of the domain you would like to check for ‘Auto-Renewal’ on. From submenu (...) click on 'Auto Renewal Status'.
On this page you can switch the Auto-Renewal on or off.
Note that non-domain services are always auto-renewing (but can of course be cancelled via your account any time prior to renewal).