A retail company is preparing a total cost of ownership (TCO) analysis for a proposed custom Copilot Studio agent that will answer employee policy questions. The finance team has already accounted for Azure consumption charges and Copilot Studio licensing. During architecture review, the Business Solutions Architect insists that the TCO is materially understated because a significant recurring cost category has been omitted. Which omitted category should the architect prioritize adding to make the TCO analysis complete?