Overview

There are yearly/monthly and pay-per-use billing modes. Each one has different advantages and disadvantages.

Yearly/Monthly is a prepaid billing mode. You pay in advance for a subscription term, and in exchange, you get a discounted rate. The longer the subscription term, the bigger the discount. Yearly/Monthly billing is a good option for long-term, stable services.
Pay-per-use is a postpaid billing mode. You pay as you go and just pay for what you use. Pricing is listed on a per-hour basis, but bills are calculated based on the actual usage duration. Pay-per-use billing is a good option for scenarios where there are sudden traffic bursts, such as e-commerce promotions.

**Table 1** Differences between billing modes
Billing Mode	Yearly/monthly	Pay-per-use
Payment	Prepaid	Postpaid
Billing Method	Billed by the subscription term you purchase	Pricing is listed on a per-hour basis, but bills are calculated based on the actual usage duration.
Billed Items	Instance specifications (vCPUs and memory), storage space, backup space, EIPs, and monitoring by seconds	Instance specifications (vCPUs and memory), storage space, backup space, EIPs, and monitoring by seconds
Changing the Billing Mode	Yearly/Monthly can be changed to pay-per-use. Auto renewal will be disabled after the billing mode of your DB instances change to pay-per-use. Exercise caution when performing this operation. Changing the Billing Mode from Yearly/Monthly to Pay-per-Use	Pay-per-use can be changed to yearly/monthly. Changing the Billing Mode from Pay-per-Use to Yearly/Monthly
Changing the Specifications	Supported	Supported
Application Scenarios	Recommended for resources expected to be in use long-term. A cost-effective option for scenarios where the resource usage duration is predictable.	Recommended when the resource demands are likely to fluctuate and you want more flexibility.