Direct answer

They are using the work. The invoice is still open. Move in this order.

A client who is merely late invites an argument about process. A client who is using the work has settled the only question that matters, whether it was delivered, and settled it in your favour. Your job now is to make that fact undeniable and dated, attach a deadline to it, and stop feeding the job. Here is the order of moves.

See the instrument first: the live demo runs one real call and hands you its verifiable receipt, no signup.

Updated October 19, 2026. The delivery record quoted below is real and public, re-checked against the live service on publication day.

Why use changes the conversation

While an invoice is just unpaid, a client can hide behind process: the file never arrived, the version was wrong, the work was not what was agreed. The moment the work is live in their product, on their site, or in their campaign, those exits close. They are not disputing delivery any more; they are benefiting from it. Everything below is about converting that fact into payment before you spend anything on escalation: facts first, record second, message third, deadline fourth, remedies last.

One: freeze the facts

Before you write to the client, assemble the trail in one place: what was delivered, on what date, through which channel, and where it is being used now. Save the live pages or posts that carry your work, with their URLs and the date you captured them. Keep your original files and the messages that sent them. If the job ran through a delivery record, this step is already done, because the record holds the steps, the times, and the delivery itself:

What a checkable delivery record looks like

That is the standard your own trail has to meet: a record a stranger can open and recompute, which states its own weak spots instead of hiding them. Against a record like that, claims like never received it or that is not the agreed version do not survive contact.

Two: send the short message

One message, in writing, with three facts and one date: the work was delivered on this date, it is live at this address, invoice number and amount are open, and payment is due by a named day. No anger, no history of the whole relationship, no threats you have not decided to carry out. Attach the delivery record or its link. Most use-without-payment ends here, because the message shows the client you can prove delivery and use, in that order, without raising your voice.

Three: stop feeding the job

While use is unpaid, nothing new flows: no extra pages, no fixes, no source files, no next stage. Say so once, plainly, and attach the restart condition, which is payment of the open invoice. New work handed over during a payment fight becomes new unpaid use, and it teaches the client that the flow never actually stops.

Four: the formal demand, then the remedies

If the date passes, send the formal version: the same facts, the delivery record, the invoice, and the date by which you will pursue the remedies your agreement and local rules give you. Those remedies, and whether you can force the work to be taken down, depend on your contract, the licence terms you delivered under, and where you and the client are. That part is a local question, and a short consultation answers it better than any page can.

What this page does not settle

Use is strong evidence, but it is not a court ruling. Whether unpaid use can be stopped, and what it is worth, turns on your written agreement, your licence terms, and your jurisdiction. This page is general information, not legal advice. A verifiable receipt proves the saved result was not changed since it was saved. It does not prove the work was correct, it does not by itself prove who owns it, and Zambo never holds your money or the client's.

Before the next job

The cheap version of this fight is the one you never have. Take a deposit before the first stage starts. Deliver through a record from step one, so delivery and use are provable on the day they happen instead of reconstructed during an argument. Keep the final files behind the balance. A client who knows the record exists rarely tests whether you can prove the work is yours and live.

Frequently asked questions

My client is using my work but has not paid for it. What can I do?

Move in this order. First, freeze the facts: what was delivered, on what date, through which channel, and where the work is being used, with the live addresses and capture dates saved. Second, write once, briefly: delivery date, where the work is live, the open invoice and its amount, and a named day for payment, with your delivery record attached. Third, stop the flow: no new work, no fixes, no source files while the use is unpaid, and say the restart condition is payment. Fourth, if the date passes, send the formal demand with the same facts and the remedies you will pursue. Use is the strongest fact in a payment fight, because the client has already answered the delivery question by publishing the work. What you can force, including takedown, depends on your agreement, your licence terms, and your jurisdiction.

Can I make them stop using the work?

Sometimes, and it depends on three things: what your written agreement says about payment and use, the licence terms the work was delivered under, and the rules where you and the client operate. Start with what works everywhere: a written notice that names the use, the open invoice, and a date, sent while the work is visibly live. Where the work sits on a platform or a host, their reporting routes are a second lever. Court routes and formal takedown notices are local questions, and this page is general information, not legal advice. The stronger your delivery record, the shorter every one of those conversations is.

What proof do I need that I delivered it and that it is mine?

A dated trail a stranger can follow: the delivery itself with its date and channel, the files as sent, the messages around them, and any acceptance the client gave. The strongest form is a verifiable delivery record, where each step of the job was saved as it ran and the record can be recomputed by anyone, so the client is arguing with arithmetic instead of with your memory. Keep your originals and your working files as well. A record proves the saved result was not changed since it was saved; ownership is a separate question your agreement and your originals answer.

Should I keep working for them while this is open?

No new work, and no quiet favours either. Every extra delivery during a payment fight becomes extra unpaid use and resets the client expectation that the flow never stops. Say it once, in writing, without heat: work resumes when the open invoice is paid. Finishing something already delivered and defective is the one exception, because a real defect is yours to fix, and fixing it is not a discount or a gift, it is the original bargain.

How do I make use without payment provable on the next job?

Build the proof in from the first step instead of assembling it during a fight. Run the job through Zambo, so every step lands on one handover link with its own verifiable receipt, the client accepts or flags each delivery on the record, and the day your work goes live there is a dated record of exactly what was delivered. For $0.99, run the next job on a recorded footing, with the delivery record building as the work happens: https://zambo.dev/day-pass/ A Day Pass covers 24 hours, no subscription. Ongoing use is the Zambo Pass at $29 a month or $290 a year, and $19 a month for $ZAMBO holders, which adds private handover links, your branding, and the approval record as PDF and JSON files.

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