The domains set for auto renewal will be renewed each year with the card details you have provided during registration.If you have opted for manual renewal, you will receive an email reminder 3 or 4 times over a span of 30 days prior to your date of renewal. On receiving this mail, you will have to login to the Zoho Mail Control Panel to renew your domain.
Login to https://www.zoho.com/mail/.
Click Control Panel.
Click Domains.
Provide your credit card details then click the Renew link.
For more details, visit https://www.zoho.com/mail/help/adminconsole/domains.html#alink4