The automatic renewal means you will be billed for your access to the software on a monthly / annual basis, or every 3 years, i.e. your credit card will be charged every month / every year, or every 3 years automatically.
After the expiration date of your subscription, the system will automatically renew it for another billing period (month/year/3 years).
The pros here are that it saves you time and effort by not having to make а new purchase every month/year/3 years and also ensures your work is uninterrupted.
You can turn off the automatic renewal until 1 day prior the renewal by logging into my.chaos.com. Learn more about disabling automatic renewal here.
You can enable the auto-renewal again until 1 day prior the renewal. Please note that it is not possible to reactivate your license once the end date has passed.