You are responsible for monitoring and renewing your domain name when the expiry date nears.
As an added service to customers we have registered domain names for, we put into place a domain renewal reminder system in which owners of domains which we have registered are sent reminder notes via email approximately one month prior to their domain's expiration date.
These notices are sent to the contact email address associated with the account. This is only one of many reasons it's important to make sure that your contact address is always a valid/active off-network address.
Note: You MUST renew your domain name at least 14 days before it expires. If you leave it past the expiry date the domain will be locked down and you will not be able to access your site.