Direct answer
How much does it cost to keep a verifiable record of every AI job?
It costs $0 to start. Work run through Zambo on the free tier leaves verifiable receipts at no charge, up to 20 free calls per metered tool per day. A Day Pass costs $0.99 for 24 hours on a heavy delivery day, and the Zambo Pass is $29 a month. There is no per-receipt fee.
By Brennan Zambo, creator of Zambo. Updated October 17, 2026.
The worksheet: three routes, three budgets
| Route | Cost | Who it fits |
|---|---|---|
| Free tier | $0 | Occasional jobs and first proof. Up to 20 free calls per metered tool per day, some tools unlimited; every call still writes its verifiable receipt. |
| Day Pass | $0.99, one time, 24 hours | One delivery, one dispute, one client who wants to check before paying. No subscription, no auto-renew. Humans pay by PayPal or card through PayPal; agents pay with USDC on Base. |
| Zambo Pass | $29 a month, or $290 a year | Daily client work: private handover links, branding, PDF and JSON export. $ZAMBO holders pay $19 a month for the same Pass. |
One worked example: a delivery day with 60 recorded calls spread across three tools stays inside the free tier while no single metered tool passes its daily free allowance, and costs $0.99 in total on a Day Pass when one does. Either way the day's record is complete; the only thing that changes is the price of the room it needed.
The costs nobody puts on the worksheet
The record itself is the cheap part. The expensive version of proof is the one you build by hand after a client asks a hard question: an evening reassembling what an AI did from chat history, screenshots, and memory, for a record the client still has to take your word for. Price that evening once, at your own rate, against $0.99. The other hidden cost is the dispute itself: a job whose record exists from the start rarely becomes an argument, and arguments are billed in days, not cents. The cheapest-way page ranks the do-it-yourself methods against this worksheet in full.
What the record costs when you build your own logging
A home-built logging system costs days to build, and then it costs trust forever, because a record you wrote about your own work is a record your client has to believe. The worksheet above buys the record and the independence together: the connection writes the receipts, the format is the published AER-1 Internet-Draft (draft-zambo-aer1-23), and the client checks it without your login.
The honest part
Free-tier limits vary by tool, and heavy daily work will outgrow them; that is what the Pass is for. Prices here are the live prices as of October 17, 2026, and the record a receipt gives you proves the saved result was not changed since it was saved, not that the work was correct. No plan changes that limit, at any price.
Frequently asked questions
How much does it cost to keep a verifiable record of every AI job?
Nothing to start. Work run through Zambo on the free tier leaves a verifiable receipt for every call at no charge, up to 20 free calls per metered tool per day, with some tools unlimited. A Day Pass costs $0.99 for 24 hours when one day of work needs more room, and the Zambo Pass is $29 a month, or $290 a year, for daily client work. There is no per-receipt fee.
Is there a per-receipt charge?
No. Receipts are written for every call the connection runs, on every tier, including the free tier. What the paid tiers buy is room and presentation: more calls in a day, private handover links, branding, and PDF and JSON export. The record itself is never metered per piece, because a proof system that charges per proof teaches people to skip proofs.
What does the free tier actually include?
Up to 20 free calls per metered tool per day, with some tools unlimited and a few tools carrying smaller daily allowances. Every one of those calls writes its verifiable AER-1 receipt, and the receipts can be checked by anyone with the link at no cost. For many freelancers the free tier covers ordinary days entirely; the Day Pass exists for the heavy ones.
When is the $0.99 Day Pass the right buy?
On the day the record has to carry weight: a delivery a client will check before paying, a dispute you are answering with evidence, or a batch of jobs that outgrows the free tier for one day. It is one payment of $0.99 for 24 hours, with no subscription and no auto-renew, so the cost of proving one important day is less than the cost of describing it twice.
Do the records expire or cost more to keep?
Receipts stay checkable by their links; keeping them does not add a storage fee on top of the tier that created them. Handovers can be exported as PDF and JSON on the Pass tiers, so you can hold your own copies of the record set as well. What you keep is the proof; what you stop paying for, if you cancel, is new capacity, not your history.
Your AI said "done." For $0.99, prove it: https://zambo.dev/day-pass/
For the same question answered as a worksheet, see the main site: how much does it cost to keep a verifiable record of every AI job, with the free route and the Day Pass route priced side by side.