ACM certificates are valid for 13 months (395 days). To be renewed, email-validated certificates require an action by the domain owner. ACM begins sending renewal notices 45 days before expiration, using the domain's WHOIS mailbox addresses and to five common administrator addresses. The notifications contain a link that the domain owner can choose for renewal. After all listed domains are validated, ACM issues a renewed certificate with the same ARN. For more information, see Renewal for domains validated by email.
You can also use automation with ACM certificates that are email-validated instead of manually validating certificates. For instructions, see Automating email validation.