This topic does not apply to Oracle Cloud at Customer.
Free Promotion subscription
You can sign up for a 30–day Oracle Cloud promotion and receive free credits. This promotion applies to eligible Oracle Infrastructure as a Service (Oracle IaaS) and Platform as a Service (Oracle PaaS) services.
See Requesting and Managing Free Oracle Cloud Promotions in Getting Started with Oracle Cloud.
Universal Credits subscription
In the Universal Credits subscription model, you commit to pay a certain amount up-front annually, based on a monthly cost estimate.
See About Universal Credits in Getting Started with Oracle Cloud.
For other subscription methods, see Buying an Oracle Cloud Subscription in Getting Started with Oracle Cloud.