You will receive e-mail notifications that your subscription for Bitdefender will auto-renew if this option is left enabled when you purchase the product from www.bitdefender.com. Automatic renewal will extend your subscription automatically before it expires, and you don’t need to go online to renew it manually.
Notifications are sent 30 days, 15 days and 7 days before your subscription expires to remind you about the auto-renewal and to provide you the option to keep or to cancel this service. A cancellation link for the subscription is provided within the email.
To get a better understanding of the auto-renewal, read this article – Bitdefender’s Auto-Renewal Service.