Overview

Dedicated HSM instances in DEW support the yearly/monthly (prepaid) billing mode. KMS and CSMS support the pay-per-use (postpaid) billing mode.

• Yearly/Monthly billing: A prepaid mode in which you pay for the service before using it. Your bill is settled based on the required period. The longer you use the service, the more discounts you got. This mode is applicable to mature services that have long-term and stable device requirements.
• Pay-per-use billing: a postpaid mode in which you pay for what you used. You are billed by second based on the actual usage. Your bill is settled by the hour. With the pay-per-use billing mode, you can easily adapt to resource requirement changes, reducing the risk of over-provisioning of resources or lacking capacity. In this mode, there are no upfront commitments required. This mode is ideal for scenarios with volatile resource demands, such as e-commerce flash sale, where resource usage fluctuates rapidly.

  Table 1 Billing modes

  Billing Mode	Yearly/Monthly Billing	Pay-per-Use Billing
  Payment method	Prepaid Billed by the purchase period specified in your order	Postpaid Billed by service duration.
  Billing period	Billed by the purchase period specified in the order	Billed by the second. A bill is generated on the hour.
  Billing items	Dedicated HSM instance	KMS and CSMS
  Changing the billing mode	The billing mode cannot be changed to pay-per-use.	The billing mode cannot be changed to yearly/monthly.
  Application scenario	This billing mode is cost-effective and suitable when the duration of resource usage is predictable. The yearly/monthly mode is recommended for long-term users.	This mode is suitable when you want more flexibility and control on resource usage.