Auto renewal is related to our billing system which will issue a new invoice 30 days before your domain expires. If a customer "Disables Auto-Renewal", then the system will send no invoice for that and the domain will eventually expire with no prior notification.
Regarding the period of the renewal, our billing system will attempt to follow the last trend, for example: If a client registered a domain for 2 years, the next renew invoice will be for 2 years.
This can of course be changed but you will need to open a Support ticket.
The clients can as well pick the period they want their domains to be renewed and this can be done at the following section: https://my.host.al/cart.php?gid=renewals