Billable cost is the amount of money invoiced to partners for using Display & Video 360. Billable cost is calculated as the sum of media costs plus any "invoiced" partner costs (such as CPM fee 1, CPM fee 2, Media fee 1, Media fee 2), and is calculated differently based the configuration of each partner.
If a fee is marked "Invoiced", the cost will appear on invoices from Display & Video 360.
The Display & Video 360 fee is a non-editable partner cost and is automatically included in a partner's billable cost. Note that Display & Video 360 fee does support a tiered rate structure.
Any CPM fees set to "0" (zero) won't show up in reports.