> ## Documentation Index > Fetch the complete documentation index at: https://neverminedag-feat-use-cases-section.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Case study: Exa > How Exa shipped autonomous-agent payments with one endpoint, no metering changes, and a static llms.txt entry — and what it means for monetizing any paid API. [Exa](https://exa.ai) is a search API used by AI agents to retrieve content from the web. Their integration with Nevermined is the live reference for the **monetize paid APIs for agents** pattern — and it works because every part of it was designed to need as little new infrastructure as possible. ## What Exa built One new endpoint. That's the whole server-side delta. | Field | Value | | -------------- | --------------------------------------------------------------------------------------- | | Endpoint | `POST https://admin-api.exa.ai/team-management/nevermined/purchase-key` | | Auth | `payment-signature` header carrying an x402 access token | | Price | \$7 per purchase, charged via Nevermined card delegation (`nvm:card-delegation` scheme) | | Response | `{ "status": "ok", "apiKey": "...", "expiresAt": null }` | | Top-up | Same endpoint, same payer wallet → existing key tops up instead of issuing a new one | | When exhausted | Regular Exa endpoints return HTTP 402 + `{ "tag": "NO_MORE_CREDITS" }` | What \$7 buys, per their integration page: | Endpoint type | Calls per \$7 | | ---------------- | ------------- | | Standard search | \~1,000 | | Deep-Lite search | \~700 | | Content pages | \~7,000 | | Deep-Reasoning | \~466 | Notice: Exa is doing all the metering. The \$7 from Nevermined is just the trigger that funds an internal balance. Search rate-limits, deep-reasoning quotas, and every other product decision stays inside Exa's existing systems — Nevermined never touches the hot path. ## Why this is strategically interesting for Nevermined Most of what Nevermined had been doing before this is monetizing **agents** — paywalling the AI service itself, charging per call. Exa flips the angle: now Nevermined is monetizing **what agents pay for to do their job**. That's a much wider surface. Every agent that runs end-to-end consumes paid services along the way — search, document retrieval, image generation, market data feeds, maps, weather, financial APIs. Each of those is a potential Exa-shaped integration. And because the provider-side cost is so low (one endpoint, no metering changes), the pattern travels well. > "We're no longer just monetizing the agents themselves — we're monetizing paid services that agents may need to complete their task. And best of all the integration is really simple." ## How agents discover the integration Exa's [llms.txt](https://exa.ai/docs/llms.txt) lists their Nevermined integration under `## Integrations` — a single line linking to a static [`nevermined.md`](https://exa.ai/docs/integrations/nevermined.md). That's the entire discovery surface. Any agent that reads the `llms.txt` (and most LLM-powered tools that fetch URLs do) follows the link, reads the integration page, and now knows how to pay for and use Exa. The integration page itself is six sections: intro / buy a key / what \$7 buys / sample request / parameters from Nevermined / when the key runs out / references. Nothing more. The structure is so small that any LLM-class agent can ingest it as part of normal context and act on it without special prompting. [How to publish your own llms.txt + nevermined.md →](/docs/use-cases/agent-discoverability) ## What this means for other providers If you're an API provider with existing metering, the takeaways: One purchase endpoint, no per-call settlement, no SDK on your hot path. The handler is the same shape regardless of which card rail (Stripe / Braintree / Visa Trusted Agent Protocol) the buyer enrolled. Exa kept their internal metering, their rate limits, their tier structure. Nevermined just adds a new top-up trigger. You can offer the same product to humans and to agents with no fork in the codebase. No agent registry to maintain, no API to call. A `llms.txt` + a `nevermined.md` on your existing docs site is the whole thing. Exa's integration page mirrors a structure you can adopt verbatim — same section headings, same fields. Agents that have seen one will navigate yours. ## Try it yourself The [`web-search-paid-api-ts`](https://github.com/nevermined-io/tutorials/tree/main/web-search-paid-api-ts) tutorial implements the Exa pattern end-to-end against a stub web-search service. Server, client, llms.txt + nevermined.md templates, README walkthrough. Clone it, point it at a sandbox PAYG plan, and you'll have an agent autonomously buying an API key in under five minutes. ## Related * [Exa's live integration page](https://exa.ai/docs/integrations/nevermined.md) * [Exa's `llms.txt`](https://exa.ai/docs/llms.txt) * [Monetize paid APIs for agents](/docs/use-cases/monetize-paid-apis-for-agents) — the pattern this case study ships * [Agent discoverability](/docs/use-cases/agent-discoverability) — how to publish your own integration page * [API Providers — implementation guide](/docs/solutions/api-providers) — the technical deep-dive