Billing/usage report perspective.As per document,"The usage_metering probe counts the number of resources that are monitored by the monitoring probes. The probe counts each monitored device as one resource."
For oracle probe "The billing report includes the number of monitored databases. If the monitored databases change within a month, the report uses the largest value."Customer reported that for the particular end customer the database monitoring has not changed for over a month and they are monitoring a few databases (more than 10).
But usage_metering probe primary hub summary report under the "Overall Billing Packs Summary" section in the "Pack Name" column for pack "CA NM - Server and Application Pack" it has a "Total Unit Count" of "5.00" with an "Referenced Probes" indication of "cluster,oracle,sqlserver,cdm".
For this count seems to be counting the installation of these probes, this because they actually have installed 1-cluster probe, 2-oracle probes, 1-sql server probe and 1-cdm probe.