The usage dashboard is a bar chart with one bar per account, sorted descending. The first time I looked at it properly, the tallest bar by a considerable distance belonged to somebody who had never paid us anything.
They were not abusing it. They were using it exactly as intended, enthusiastically, every working day, for a job they genuinely had. They were, in the language of the old playbook, a fantastic signal. They were also, in the language of the invoice from Lesson 7, our third largest cost.
This is the part of the AI business model that catches people who learned software economics before 2023, and it catches them somewhere around month five.
The free user used to be free
In classic software a free user costs a row in a database, some storage, and a fraction of a shared server. The marginal cost is genuinely close to zero, which is why the freemium model became near universal. You could carry a hundred thousand free accounts on the same infrastructure that served your paying ones and barely notice.
That is no longer true, and the change is not subtle. A free user in an AI product consumes inference on every request, at the same rate as a paying one, and there is no version of the architecture where that goes away. A heavy free account can cost you more per month than a median paying account generates.
The consequence is that a free tier is no longer a marketing decision with a rounding error attached. It is a spending program, and it belongs in the same conversation as any other spending program: what is it buying, how much is it costing, and how would we know if it stopped working.
What free is actually buying
There are three legitimate answers and you should be able to name yours in one sentence.
Distribution. Free users tell other people. This works when the product is visible in use, when the user has an audience, or when the output carries your name somewhere. It works poorly for internal back-office tools, which is most business software.
Data. Usage improves the product in a way that benefits paying customers. This is real, and it is the strongest argument, but it only holds if you are actually capturing and using the signal. A free tier that generates logs nobody reads is not buying data, it is generating logs.
Qualification. Self-service reduces the cost of finding buyers. The free tier does the first three sales calls for you, and the people who arrive at your pricing page have already decided. This is the most common real answer and the easiest to measure.
If none of those three describes what you are doing, you have a free tier because everybody has a free tier. That is a preference, not a strategy, and now it has a monthly cost attached to it.
Designing a loan rather than a gift
Five design choices do most of the work.
- Route free traffic to the cheaper model tier. The routing discussion from Lesson 7 applies with more force here. A quality difference that would be unacceptable in a paid product is entirely acceptable at a price of zero, and it can cut the cost of your free tier by most of it. Be honest about it in your documentation rather than hiding it.
- Cap by unit of value, not by time. Fourteen days of unlimited access rewards the person evaluating you least seriously, because the serious evaluator needs three weeks to get their data in order. Ten documents, or fifty runs, or one project is better: it survives a slow start, it maps to something the user understands, and it costs you a bounded amount.
- Rate limit, and show the limit. A visible counter is not a hostile act. It converts better than a silent ceiling because it tells the user what the paid version is for.
- Require something. An email address costs a user nothing. A work email costs slightly more. Connecting a real data source costs real commitment and filters hard. Ask for the largest thing you can justify at the point where the user is about to receive value.
- Measure it as a cohort and be willing to end it. Cost per free user per month, conversion rate by cohort, and time to convert. If a cohort has not converted in ninety days, it probably will not, and continuing to serve it is a decision you should be making on purpose.
The trial alternative
Freemium is not the only option and it is frequently the wrong one for business software with real serving costs.
A time-boxed trial of the full product, with payment details taken up front, does most of what freemium does at a fraction of the cost and with a far better conversion rate. Taking the card is not a trick, it is a filter, and the people it filters out were unlikely to buy.
The reverse trial is worth knowing about too: full functionality for a short period, then automatic downgrade to a genuinely limited free tier rather than a wall. The user has felt the good version and lost it, which is a much stronger motivator than never having had it, and your ongoing cost sits at the limited tier rather than the full one.
Three ways this goes wrong
You build a free tier that is good enough. The most expensive version of this mistake is not the compute bill, it is that you have shipped a competitor to yourself, staffed it, and given it away. If a meaningful share of your free users are getting the job done without paying, the tier is not a funnel, it is the product. Find the line where value becomes real and put the wall exactly there.
You underestimate abuse. A product that turns requests into money spent is an attractive target. Keys embedded in client-side code get scraped. Accounts get created in bulk. Somebody discovers your endpoint is a cheaper route to a frontier model than paying for one directly. This is not hypothetical, it is a normal Tuesday, and the defenses are ordinary: server-side keys, per-account and per-address rate limits, anomaly alerting on cost rather than on traffic, and a hard spend ceiling with somebody’s phone number attached.
You never calculate the cost per free user. It is one division and almost nobody does it. Total free-tier inference spend divided by monthly active free accounts. Put that number next to your conversion rate and your average contract value and you can answer, in about thirty seconds, whether the program is an investment or a habit.
We kept our free tier, narrowed it substantially, and routed it to a cheaper model. Conversion went up. That was not the outcome I expected and it is the one most teams report, which suggests the generous version was never doing the work we imagined.
Every free user is a loan you make in compute and hope to repay in conversion. Know the interest rate.
Tomorrow: the runway model, and the two clocks that run at different speeds.