After signing the contract, it's essential to monitor the performance of your cloud vendor regularly. To do this, you should use various tools and methods to track and analyze usage, quality, security, and satisfaction metrics. Usage metrics should compare your expectations and budget with actual usage. Quality metrics should compare the SLA and your requirements with the cloud services' performance. Security metrics should compare industry standards and regulations with your data, applications, and users' security in the cloud. Finally, satisfaction metrics should compare your goals and expectations with the vendor's performance, support, and communication. With these metrics, you can optimize usage, improve quality and efficiency, detect and prevent security incidents and risks, as well as provide feedback and suggestions.