Scheduled Instances enable you to purchase Amazon EC2 compute capacity by the hour for a one-year term. Before you can purchase a Scheduled Instance, you must call DescribeScheduledInstanceAvailability to check for available schedules and obtain a purchase token. After you purchase a Scheduled Instance, you must call RunScheduledInstances during each scheduled time period.
After you purchase a Scheduled Instance, you can't cancel, modify, or resell your purchase.