For fixed traffic scenarios, Prepaid is generally the better choice to manage costs effectively. *Prepaid*: Prepaid billing allows you to pay for your cloud resources in advance based on your estimated usage. This mode is well-suited for services with relatively fixed traffic because you can plan and budget for your computing resources, and you won't be charged for usage beyond what you've prepaid. It provides cost predictability and stability. *Pay-As-You-Go*: Pay-As-You-Go billing is typically more suitable for services with variable or unpredictable traffic patterns because you pay for the resources you use on an hourly or monthly basis. While it offers flexibility, it can be more expensive if your traffic is relatively fixed because you're billed based on actual usage.

Subscription instances require upfront payment, which must be completed before each billing cycle. https://www.alibabacloud.com/help/en/elastic-compute-service/latest/billing-methods-subscription

In general, if traffic volume is relatively fixed and predictable, and you want to ensure that you have sufficient resources available to handle your traffic needs, a prepaid charging model may be a more appropriate choice. Usually, you will receive discount for prepaid charging model

pay-as-you-go