AWS KMS keys are used with the AWS Key Management Service (AWS KMS). You're billed for all active or deactivated KMS keys on your account. You're also charged for the API requests that are made to the AWS Key Management Service (AWS KMS) out of the AWS Free Tier usage.
To see a list of KMS keys on your account, choose Customer-managed keys in the AWS KMS console. To stop the charges for the KMS key, delete the KMS key.
Warning: If you delete the KMS key, then any services that you configure to use the KMS key as part of their function are affected.