Oracle said it will add AI usage charges to its subscriptions. CFOs must budget for work as well as users.

"The more work that gets done by AI in our system, the more revenue we will see because they're consuming AI units as that work is getting done," Leone said. "We don't have to add more seats in order for us to now generate more revenue."

Oracle gave no price per AI unit and no start date. The Register wrote that the plan promises more revenue for Oracle and higher bills for customers.

Oracle is also spending heavily. It put $55.7 billion on data centres and cloud infrastructure in the fiscal year to May, and plans $90 billion to $95 billion in fiscal 2027.

For a CFO, an application bill has mostly been seats, meaning paid user accounts, times a price, known a year ahead. AI units tie part of that bill to how much work the software does. Oracle has published no unit price, so that part of the bill cannot be calculated yet. Our reading: the contract question moves from how many users there are to who may switch on an AI agent, and whether its spending has a cap.