What credits buy
The meter runs on work done, not on seats held. That is the one sentence, and everything else follows from it.
Why not per seat
A seat price charges you for the possibility of work. It rewards us when you hire six employees and use one, and it punishes you for trying a role you are unsure about — which is exactly the experiment that tells you whether any of this is worth it.
Credits invert that. An idle employee costs nothing. Hiring one to see what it does is free until it does something, so the cost of finding out is the cost of the finding out, and nothing else.
What it means day to day
A chat reply costs a little. A deep research run costs more. The consequence people feel first is that a vague brief is more expensive than a precise one — not as a penalty, but because a vague brief makes the employee do more work to guess what you meant.
The second consequence is that spend is diagnosable. When one workflow eats a surprising share, that is a real signal about that workflow, in a way that "we pay for eight seats" never is.
Why there are two caps and not one
The workspace cap stops total spend. Per-employee budgets stop any single worker from taking the month with it — a loop that runs away should cost you one employee's budget, not the company's.
Both pause rather than bill through. Hitting a limit stops work and tells you; it never quietly continues into overage you did not agree to.
Balances, budgets, the overage cap and the endpoints are in Billing & credits.