Domains are renewed annually. Read How to check a domain's renewal or expiration date to find the date of your renewal.
Note: Your domain will renew automatically 30 days prior to the expiration date if you have auto-renew turned on and your payment method is valid. If there is an issue with your card the renewal will not happen. Additionally, .realtor domains require that you are a member in good standing with NAR or CREA. If your NAR or CREA membership is inactive you will not be able to renew your domain until you contact them and resolve your membership status.