Windows 10 Enterprise LTSC -Activation key

Question

Good day,

I use Windows 10 Enterprise LTSC Edition 2021 - Evaluation. Now (27th December 2025, 10:25 am Prague Time Zone) is fully update to Servicing Stack 10.0.19041.6449.

I am going to full update to KB5071546 (December 2025 Update for non very often using Windows 10).
For this step, it is requirement to install the Servicing Stack 19045.6466 Out-of-band.At now, this OS Windows 10 Enteprise LTSC Edition 2021 - Evaluation is not activate.

Can I use official KMS client Product key: M7XTQ (first part of key) - J462D (final part of key)?

I read that the Activation is requirement to install the latest update KB5071546 and later.

Regards

Mr. Jan Stocek

Liberec

Czech Republic

Answer 1

Dear Jan Stocek

Thank you for the clarity you provided about your current servicing stack version and your plan to install KB5071546.

The Evaluation edition of Windows 10 LTSC is designed for testing purposes and does not support activation with standard KMS client product keys such as the one you mentioned (M7XTQ-…-J462D). Those keys are intended for use with fully licensed, non-evaluation editions of Windows. Because the Evaluation edition cannot be activated, you will not be able to apply cumulative updates like KB5071546 once activation becomes a prerequisite.

If you require ongoing updates and long-term servicing support, the recommended path is to install a fully licensed LTSC edition rather than continuing with the Evaluation build. Once you deploy the licensed edition, you can use the official KMS client key to activate the system against your organization’s KMS host or Microsoft activation services. After activation, the servicing stack update (19045.6466) and cumulative update KB5071546 should install without issue.

In summary, activation is indeed required for the latest updates, but the Evaluation edition cannot be converted to a licensed state using KMS keys. Transitioning to a licensed LTSC edition will ensure compliance and access to future updates.

I hope this clarifies the situation and helps you plan your next steps. If you find this answer helpful, please don’t forget to hit “Accept Answer” it helps us know we’ve addressed your concern.

Answer 2

Yes, you can use the official KMS client product key for Windows 10 Enterprise LTSC 2021, which is M7XTQ-FN8P6-TTKYV-9D4CC-J462D. This key is specifically designed for KMS activation of the Windows 10 Enterprise LTSC edition. Since you mentioned that your evaluation version is not activated, using this key will allow you to activate your system, which is a requirement for installing updates like KB5071546.

Make sure to enter the full product key using the command prompt with administrative privileges:

slmgr /ipk M7XTQ-FN8P6-TTKYV-9D4CC-J462D

After entering the key, you should be able to proceed with the activation and subsequent updates.