Billing by not building billing: the commercial model is a property of the key

A user pays five pounds through a payment link; the company keeps its cut at the moment of payment; the rest becomes the credit limit on a key handed to the user; the provider meters it and the key stops when it is spent. Against a billing system (a meter on every call, a ledger per user, disputes, refunds, fraud, custody of the data while it meters) that is a payment, a cut, a key with a ceiling and nothing else, and it is more profitable per pound because the margin is taken once, up front. The minimum top-up is five pounds because a card fee with a fixed component makes a one-pound purchase return about 59 pence of inference.

Decided by. Nobody yet: a candidate for Dinis to read, comment on and decide (keep, rewrite, merge, cut, article first, later, not doing it).

Note. Could also sit in price-it-then-give-it-away. The model was written down on 28 July 2026, the day the product started, in a brief headed 'Billing by not building billing'. It is why a router like OpenRouter does well: it sells credit, keeps a margin and meters for everyone else. The user owns the ceiling: a key with a limit cannot cost more than the limit, and the user can revoke it at the provider in one click.

Where it comes from

The key is the billing system The commercial model that was never a billing system (newsroom)

What it answers in the 2018 book

none named

Where it goes

Chapter Ship a serverless product in a weekend, part Hands on, 2026 (drafting); topic Be a founder (or a one-person service).

Other ideas proposed for the same chapter: Three honest tiers for a model on a site with no server: a local matcher, your own key, or a vault bridge, Scope the feature to one question, and quote rather than paraphrase, Twice now the product was possible and the licence was the blocker: read the terms, not only the docs, VoiceDebrief: a product with no server that shipped in three weeks and stopped at the one thing it could not sell, A read-only vault needs no code; a read-write vault server is 83 lines on a free plan.

Node idea:billing-by-not-building-billing in graph.json; see it in the graph. Source: admin/content/graph/ideas.json.