# 0xC004C008: Key usage limit exceeded

> Source: https://karincalisans.com/en/windows-error-codes/0xc004c008/ · Updated: 2026-07-31 · Publisher: Karınca Lisans

0xC004C008 tells you the product key has already been used on the allowed number of devices. It appears when a single-device key is activated on a second computer, or when the same key was previously entered on another installation. If the key will live on only one device, phone activation usually resolves it; otherwise contact your seller.

## Most common causes

- A single-device key was entered on a second computer
- The same key was used on another installation in the past
- The key was sold to multiple people (untrustworthy source risk)

## Step-by-step fix

1. Make sure the key is used on a single computer; if the old device is retired, continue.
2. Press Windows + R → "slui 4" for phone activation; if the key can move to a single device, the wizard issues a confirmation ID.
3. Run Settings → System → Activation → "Troubleshoot".
4. If the error persists, contact your seller and ask them to check the key's usage history; invoiced purchases qualify for replacement.

## Frequently Asked Questions

### Can I use the same key on two computers?

Individual Windows keys are for a single device. Two computers require two licenses; anything else produces this error and activation revocations.

### I replaced my computer and my old key throws this error. What now?

The phone activation wizard is designed for this scenario: if the old device is out of use, try confirming the key on the new installation through the wizard. If that fails, clarify your license type's transfer terms with your seller.