As of today, customers are able to provision Azure Red Hat OpenShift clusters without being required to purchase reserved instances for their application nodes.
Master nodes, infrastructure nodes, application nodes run on Azure Virtual Machines, billed at Linux VM pricing. Compute, networking and storage resources consumed by your cluster are billed according to usage. In addition to the compute and infrastructure costs, application nodes have an additional cost for the OpenShift license component. This is billed based on the number of application nodes and the instance type.
All standard Azure purchasing options, including reservations and monetary commitment can be used for Azure Red Hat OpenShift and for virtual machines, networking and storage resources consumed by your cluster.
Azure Red Hat OpenShift pricing