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.

Field	Required	Meaning
team	yes	Budget holder, usually one service or product team
cap	yes	Maximum prepaid tokens for the envelope
used	yes	Cumulative actual usage.total_tokens consumed
owner	yes	Named person who approves top-ups
expires	no	Epoch seconds; after this the envelope blocks new calls
top-up reason	no	Free text required before the cap is raised

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.