---
title: "Buy one month of the paid API plan from the balance"
method: POST
path: "/api-plans/pro/subscribe"
tags: ["General APIs with JWT"]
---

# Buy one month of the paid API plan from the balance

`POST /api-plans/pro/subscribe`

## Request

- Base URL: `https://lium.io/api`
- URL: `https://lium.io/api/api-plans/pro/subscribe`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-API-Key`

Charges the plan's monthly price from the balance; an active subscription is extended by a month. An `Idempotency-Key` header makes a retry safe: the same key returns the first answer instead of a second month.

## Headers

- `Idempotency-Key` string

## Response `200`

Successful Response

- ApiPlanResponse
  - `plan` 'free' | 'pro', required
  - `display_name` string, required
  - `rate_limit_multiplier` integer, required
  - `endpoints` string[], required
  - `expires_at` string, date-time, nullable, required
  - `pro_usd_per_month` number, required

## Other responses

- `402`: The balance does not cover the monthly price, or the API key's budget is reached
- `404`: API plans are off
- `409`: The paid plan has no price yet

## Changes

- **2026-10-21** `50ab46bcf4ac`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/lium/apis/lium-backend-api/changes/api-plans/pro/subscribe/post.md)

---

[API](https://skmtc.dev/lium/apis/lium-backend-api.md) · [All operations](https://skmtc.dev/lium/apis/lium-backend-api/llms.txt) · [OpenAPI document](https://skmtc.dev/lium/apis/lium-backend-api/revisions/5656250194ce?raw)