Setting up Microsoft 365 with a product key

The product key itself is valid for setup; the issue is occurring at the payment/recurring‑billing step, not with the key.

To complete setup, use one of these approaches:

1. Redeem the product key directly

• Go to https://www.microsoft365.com/setup (or https://setup.office.com/).
• Sign in with the Microsoft account that will own the subscription.
• Enter the 25‑character product key.
• When prompted for payment/recurring billing, try:
  • A different browser (or InPrivate/Incognito window).
  • Disabling browser extensions such as ad‑blockers or script blockers.
  • A different network (for example, mobile hotspot instead of current Wi‑Fi).
• Continue until the key is associated with the Microsoft account. After redemption, install Microsoft 365 from the Microsoft account Services & subscriptions page.

2. If the “prove you are human” window still hangs

• Since the CAPTCHA step is blocking the Save action, and the context shows similar cases being resolved by changing payment method, try:
  • Using a different payment card or payment method.
  • Removing and re‑adding the card in the payment step.
• If the page still does not proceed after solving the CAPTCHA, contact Microsoft Support for direct help with the billing/verification flow, as this is not a product‑key error but a payment/authentication issue.

Once the key is successfully redeemed and tied to the Microsoft account, Microsoft 365 can be installed and activated by signing in with that account; the product key will not be needed again.

References:

• Using product keys with Microsoft 365
• Activate Office for Windows
• Trying to use an Office365 product key and "getting error PaymentAuthenticationVerificationFailed" - Microsoft Q&A