---
title: "Add $999 of prepaid balance to an API key (Pro)"
method: POST
path: "/v1/keys/upgrade/pro"
---

# Add $999 of prepaid balance to an API key (Pro)

`POST /v1/keys/upgrade/pro`

## Request

- Base URL: `https://api.limitguard.ai`
- URL: `https://api.limitguard.ai/v1/keys/upgrade/pro`
- Auth: API key in header `X-API-Key`

Credit $999 of prepaid balance to your API key and set the Pro label for 30 days (paying again extends it; the balance never expires). Each priced call is debited at the account price in the table. Pay via x402 USDC.

## Request body

- object: No body. Send X-API-Key to name the key to credit.

## Response `200`

Success

## Other responses

- `402`: Payment required. The x402 v2 challenge is in the base64 PAYMENT-REQUIRED header and the JSON body; pay and retry with PAYMENT-SIGNATURE. Prepaid balance cannot pay for a purchase.

---

[API](https://skmtc.dev/limitguard/apis/limitguard-ai.md) · [All operations](https://skmtc.dev/limitguard/apis/limitguard-ai/llms.txt) · [OpenAPI document](https://skmtc.dev/limitguard/apis/limitguard-ai/revisions/8f9718bce4a1?raw)