This topic describes the billing information about Key Management Service (KMS). The billing information includes the billing methods, billing cycles, billable items, expiration description, and renewal description.
Background information
KMS provides default key management capabilities for server-side encryption of cloud services free of charge. You can directly use the default key management capabilities without the need to purchase a KMS instance. If you want to increase the number of customer master keys (CMKs), use Secrets Manager, or build an application-layer cryptographic solution for self-managed applications, you must purchase a KMS instance whose key management type is software key management or hardware key management. For more information about how to purchase a KMS instance, see Purchase an instance.
Billing overview
The actual prices on the buy page shall prevail.
Billing method: subscription.
Billing cycle: A billing cycle is the subscription duration of an instance and is based on UTC+8:00. A billing cycle starts from the time when a subscription instance is purchased or renewed and ends at 00:00:00 the next day after the expiration date. The start time is accurate to the second.
Billable items: You are charged based on instances. If the default specifications of an instance cannot meet your requirements, you can change the default specifications of the instance based on your business requirements when you purchase the instance. The following figure shows the billable items of KMS. 
Overdue payments
KMS uses the subscription billing method. Therefore, no overdue payments can occur. You can purchase, upgrade, or renew an instance only if your account balance is sufficient.
Expiration description
If your KMS instance expires, the instance is immediately disabled and no longer provides services. Your KMS instance is released on the 16th day after your KMS instance expires.
You can go to the Log on to the KMS console and view Remaining Period of your KMS instance on the Keys page. To prevent negative impacts on your business, we recommend that you renew your instance before the expiration date.
Refunds
KMS supports partial refunds for KMS instances that are in the Disabled state and refunds for renewal orders that have not taken effect. Before you unsubscribe from your KMS instance, we recommend that you understand the unsubscription rules, precautions, and unsubscription cases.
If you want to unsubscribe from a KMS instance, contact us by using ticket.
Resource usage and bills
You can query and export KMS bills and resource usage details in User Center.
Renewal description
Log on to the KMS console. In the top navigation bar, select the required region. In the left-side navigation pane, click Keys.
Click the Software Key Management or Hardware Key Management tab, find the instance that you want to renew, and then click Renew in the Actions column.
On the Dedicated KMS | Renew page, configure the Subscription Period parameter. Then, read and select Dedicated KMS Terms of Service.
Click Buy Now and complete the payment.
Billing FAQ
Does KMS support free trials?
No, KMS does not support free trials.