On the Options tab, there is an option to "Auto Close Work Orders"

A Work Order in ProCalV5 is a collection of 'Scheduled Tasks' that have been assigned. When the last Task is completed (Closed), and the Company option of "Auto-Close Work Orders" is checked, the system will set the Work Order's Status to the Company's Default 'Closed' Status. 

Note - The Company's Default 'Closed' Status must be set on the Company screen, Additional Info tab.