Before You Give a Team an LLM Endpoint, Issue a Prepaid Token Envelope

Most internal LLM projects do not die because the model was wrong. They die because the platform team could not answer a boring question: which team consumed the quota, why, and what happens when it is gone.

Seat licenses make that question worse. They bill per developer but incur cost per token, so a team running long evals and a team calling the endpoint once a month pay the same amount. The durable fix is a prepaid token envelope: a named team gets a finite token cap, an owner, an expiry, and a top-up rule. Actual usage is debited from the envelope, and the next token is refused unless the owner requests a top-up with a reason.

A zero-cost endpoint is the cheapest place to pilot that envelope before real money or chargebacks are involved. One candidate is MonkeyCode, an open-source project described as offering free model access and a free server option, with a 30-million-token allowance in the outreach material.

Disclosure: This article was prepared as part of MonkeyCode's product outreach. The 30-million-token figure is operator-supplied, and I did not independently benchmark current limits or quotas. Treat it as a variable to confirm before you commit real workload.

Why seat licenses misprice model access

A seat license is a proxy for usage, and it is the wrong proxy for LLM cost. It creates one of two failures:

• High-usage teams are cross-subsidized by low-usage teams, so nobody sees the true cost of their experiments.
• Low-usage teams avoid the endpoint because the marginal seat price feels too high for a rare call, even when the actual token cost is negligible.

Per-token metering fixes the unit but creates approval fatigue. If a team must ask permission for every 10-cent eval, the platform team becomes a human billing API.

A prepaid envelope sits between those two failures. The team owns a fixed token budget and can spend it without an approval flow. The only question that requires a human decision is the top-up. That moves platform review from “can this request run?” to “what changed that justifies a new budget?”

The envelope fields that make it a governance tool

An envelope is only useful if it has an owner, an expiry, and an audit path. The fields below are the minimum I would require before issuing the first test envelope.

The cap is not a cost-control number. It is a governance interval: it determines how often the platform team has a forced conversation with the consuming team.

A 1-million-token envelope at roughly 2,000 tokens per request is about 500 requests. If a team asks for two top-ups in one week, the problem is not the model price. The problem is that nobody reviewed the workflow before the second top-up.

Pilot the escrow on a zero-cost endpoint

The script below is a minimal token escrow for any OpenAI-compatible chat completions endpoint. It loads a JSON envelope store, calls the model, debits actual usage.total_tokens, warns at 80%, and blocks after the cap is exceeded.

It is a single-process pilot tool, not a production billing service. Run it against a free endpoint such as MonkeyCode's free server while you validate the envelope rules.

#!/usr/bin/env python3
"""Small TokenEscrow that debits a team's prepaid envelope after each OpenAI-compatible call."""

import json
import os
import sys
import time
import urllib.error
import urllib.request
from pathlib import Path

BASE = os.environ.get("MODEL_BASE_URL", "https://your-endpoint.example/v1").rstrip("/")
KEY = os.environ["MODEL_API_KEY"]
MODEL = os.environ.get("MODEL_NAME", "default")
ESCROW_FILE = Path(os.environ.get("ESCROW_FILE", "escrow.json"))

def load_escrow():
    if ESCROW_FILE.exists():
        return json.loads(ESCROW_FILE.read_text())
    return {}

def save_escrow(data):
    ESCROW_FILE.write_text(json.dumps(data, indent=2))

def call_model(payload):
    req = urllib.request.Request(
        f"{BASE}/chat/completions",
        data=json.dumps(payload).encode(),
        headers={
            "Authorization": f"Bearer {KEY}",
            "Content-Type": "application/json",
        },
        method="POST",
    )
    try:
        with urllib.request.urlopen(req, timeout=60) as resp:
            return json.loads(resp.read().decode())
    except urllib.error.HTTPError as exc:
        print(exc.read().decode()[:500])
        raise

def spend(team, payload):
    escrow = load_escrow()
    if team not in escrow:
        raise SystemExit(f"missing envelope for team: {team}")

    entry = escrow[team]
    if entry.get("expires") and time.time() > entry["expires"]:
        raise SystemExit(f"{team} envelope expired")
    if entry["used"] > entry["cap"]:
        raise SystemExit(f"{team} envelope exhausted before request")

    body = call_model(payload)
    tokens = body.get("usage", {}).get("total_tokens", 0)
    entry["used"] = entry.get("used", 0) + tokens
    save_escrow(escrow)

    if entry["used"] / entry["cap"] > 0.8:
        print(f"warning: {team} used {entry['used']}/{entry['cap']} tokens")
    if entry["used"] > entry["cap"]:
        print(f"top-up required: {team} over cap by {entry['used'] - entry['cap']}; owner: {entry.get('owner', 'unknown')}")
        raise SystemExit(1)
    return body

if __name__ == "__main__":
    if len(sys.argv) < 2:
        raise SystemExit("usage: python token_escrow.py TEAM [PROMPT]")
    team = sys.argv[1]
    prompt = sys.argv[2] if len(sys.argv) > 2 else "ping"
    body = spend(team, {
        "model": MODEL,
        "messages": [{"role": "user", "content": prompt}],
    })
    print(json.dumps(body, indent=2)[:1000])

Create an escrow.json with one envelope per team:

{
  "platform": {"cap": 5000000, "used": 0, "owner": "platform-lead", "expires": null},
  "mobile": {"cap": 1000000, "used": 0, "owner": "mobile-lead", "expires": null}
}

Then run:

export MODEL_BASE_URL='https://your-free-endpoint.example/v1'
export MODEL_API_KEY='your-key'
export MODEL_NAME='your-model'
export ESCROW_FILE='escrow.json'
python token_escrow.py mobile 'summarize this issue'

Read the top-up reason as the actual decision gate

The point of the enclosure is not the number. It is the reason written on the top-up request.

A useful top-up reason names the changed variable: “I reran the 120-case golden set after changing the prompt template; actual usage was 1.4M tokens.” That is easy to approve because it connects spend to an evaluation.

A weak top-up reason is “more experiments” or “the team needs it.” That should not expand the envelope. It should open a working session about which experiment, which metric, and which stop condition.

If you apply one rule, it should be this: never raise a cap without a dated reason attached to a named owner. The reason is the artifact you review later when the project gets expensive.

Limitations and who should not use this

This escrow script is not a production billing system. It debits after the response, so a concurrent burst can overshoot the cap. A production version needs a reservation step before the call and an idempotent reconciliation step after it.

A free server also does not prove throughput, latency, security, or uptime. Do not use a shared free endpoint for sensitive data, deterministic latency requirements, or production failover. Use it to validate the envelope mechanics, the owner chain, and the top-up question while the financial risk is still zero.

If you want a zero-cost place to try the workflow, MonkeyCode's free server is one candidate; the reusable part is the envelope, not the vendor name.