how do i activate my Microsoft office professional with my key

Hi, DC Mac

Welcome to Microsoft Q&A forum.

Thanks for your question. An “LTSC” key is a volume license meant for organizations, it does not activate the same way as a personal Office purchase tied to a Microsoft account. On Mac, Office LTSC is activated using a Volume License (VL) Serializer, not by typing a product key into the apps.

Here are some suggestions you can try to resolve this issue:

1) If this is truly an Office LTSC license for Mac (work or school)

Use the VL Serializer to activate it:

• Have your Microsoft 365/volume licensing admin download the VL Serializer from the Microsoft 365 admin center under Billing > Your products > Volume licensing > Download and keys.
• Run the package on the Mac where Office is installed, after that Office should stop prompting for activation.

Important note: the serializer you download must match the Mac LTSC product (for example “Office LTSC for Mac 2024”), otherwise activation will not line up.

2) If you were trying to use a “Professional Plus 2024 / LTSC” key for personal use

That key type is typically not meant to be linked to a new Microsoft account or redeemed like a home purchase, it is intended for corporate volume licensing. If you bought it from a third-party seller, the practical next step is to go back to the seller for a replacement or refund, and get a legitimate Mac-compatible license.

3) Make sure you did not install the Mac App Store version (common blocker for perpetual or volume licenses)

Office apps from the Mac App Store are not compatible with one-time purchases or volume license activation. Uninstall those apps and install Office using the Microsoft installer instead.

4) If you actually have a normal Office or Microsoft 365 license (account-based activation)

In that case you do not enter an LTSC key inside the Mac apps, you activate by signing in:

Open Word (or any Office app) > Get Started > Sign in, then sign in with the account that holds the license.

Hope this helps. Feel free to get back if you need further assistance.

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