Based on your organization and users Capacity, pricing must be planned. Pro Users are required to collect, model, authors the reports and dashboards and publish to web services for sharing and collaboration will be charged. Frequent Users are just consumers of reports and dashboards, Time frame of a week probably several. These users can have free license to access Reports and Dashboards as App Workspace is backed with Premium capacity. Occasional Users are end-users where they very rarely use reports and dashboards. These users can have free license to access Reports and Dashboards  as App Workspace is backed with Premium capacity.