So I contacted the 3rd party for a refund, and instead they resolved the issue in literally 5 minutes. Microsoft lied. It was not a wrong product key. It was a known bug with Office 2019 that they are not only trying to hide, but are actively using to steer customers away from 3rd party purchases of perpetual licenses and toward Office 365 instead. Active Directory-based activation can activate Office installed on domain-joined computers. The product key information, which is the same that is used by KMS, is stored in Active Directory and replicated throughout the forest. If Office can't contact Active Directory for activation, Office tries to activate by using KMS. There is no need for the Product Key. The problem is when you have multiple installations of Office with same Microsoft Account. It also means you cannot change the Product Key (licence) with the option at the Office Account at>File>Account>Change Licence. PS: like here: Change your Office product key (microsoft.com) Method 3. Completely Remove all Office versions and re-Install MS OFFICE. Method 1. Remove Office Activation Prompt by Removing Wrong License. The first method to stop Office to prompt you to activate an old Office 2016/2019 license, is to remove the license from your computer. 1. Close all Office programs. 2. Open Command Prompt as Change Product Key for Click-to-Run and MSI based Office installations. When you are using a Click-to-Run based installation of Office or want to change the Product Key via a command line, you can use the same OSPP.VBS script as mentioned before. Step 1: Add the new key Instead of using the /dstatus switch, you must use the /inpkey:value switch Do you have a MAK key for the Office Professional Plus 2019? If yes, you may activate Office by using the product UI after finishing the installation. Besides, running ospp.vbs script is also helpful. Please search CMD, right-click the Command Prompt and run as administrator. Then copy and paste the command, click Enter at last: If you do have the key and need install help, see Install Office 2010 and Activate Office 2010. Office came pre-installed on my computer If Office came with your PC, Mac, Laptop, or tablet, look for the product key on the Certificate of Authenticity that came with your computer. If you have a home product and it came with a product key*, before installing for the first time (or sharing it if you have Microsoft 365 Family), you need to redeem your product key first. Go to office.com/setup and sign in with an existing or new Microsoft account and then enter your product key to redeem it * . [Microsoft Office] How to activate one-time purchase Office Home & Business (ex: Office 2021, or 2019) This article describes how to activate a one-time purchase version of Office Home & Business (ex: Office 2021, 2019, etc.), and you also can refer to the Microsoft’s Activate Office topic. Before activating Office, please check below Office 7kyyF.

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