Every tool claims ROI. None of them shows a receipt.
Ask any software vendor what their product is worth and you'll get a case study. Ask the machine and it opens a ledger: its bill on one line, and underneath — walk-ins it seated (measured off the check-in-to-chair pipeline at each artist's real rate) and leads it landed in chairs. A monthly total, on the shop's own board, computed from the shop's own data. Estimates wear a tilde; nothing pretends to be a receipt that isn't.
Attribution you can argue with
The tab only counts what the machine demonstrably touched: a walk-in who joined through the wall and reached a chair; a lead that arrived through the board and reached a deposit. Revenue the shop would have gotten anyway — the regular who texts their artist directly — is deliberately left out. Undercounting is the point: when the conservative number beats the bill, there's nothing to argue about.
The guarantee with teeth
Because the number is honest, it can back a promise: if a month's machine-money doesn't beat the machine's bill, the difference is credited. It pays for itself or we pay you. No software vendor makes that offer on top of a self-reported metric — it only works when the meter runs on the customer's side of the table.
Why this is the whole sales pitch
A shop owner doesn't want a demo; they want to know if the thing pays rent. The Machine's Tab turns that conversation into a card on their own home board that answers it monthly, forever. The first month it reads PAID FOR ITSELF ×3, the software stops being a cost and becomes a coworker with a good week.