View Monthly vs. Upfront Microsoft Azure Reserved Instances
You can pay for Microsoft Azure Reserved Instances (RI) either up front (pay the full amount) or on a monthly basis.
For RIs paid monthly, the total cost of the reservation is divided evenly over each month of the RI term (1 or 3 years). The total cost of upfront and monthly reservations is the same, and you don't pay any extra fees when you choose to pay monthly. When you renew a reservation, you can change the billing frequency from upfront to monthly.