The primary measurement of success for a Renewals Manager is the renewal success rate, which is the percentage of customers who renew their contracts with Cisco at the end of their term. The renewal success rate reflects the Renewals Manager's ability to retain customers and revenue, as well as to increase customer satisfaction and loyalty. The renewal success rate is calculated by dividing the number of customers who renew by the number of customers who are eligible to renew in a given period. The renewal success rate is different from other metrics such as upsell percentage, percentage of contracts closed, or iARR rate, which are not directly related to the Renewals Manager's role or performance.