The service fee for Endpoint Management Tools is $2.45 per workstation, billed monthly. 

Any Windows computer or device managed with Configuration Manager will be billed if it has been marked as active (that is, having had normal communication with the Configuration Manager infrastructure) within the last 30 days.

Any Mac computer or iOS device that maintains a computer object in the Jamf Casper instance will be billed.

Rates are the same for Windows and Mac workstations.