Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi Nadja,
I'm Michelle and I'd be glad to help you out with your query or concern.
As per Technet Office Support, please note that One-time purchases of Office: Office Home & Business, Office Home & Student, and Office Professional can be installed on a single computer. If you try to install and activate these versions of Office on a different computer (owned by you or someone else), or on the same computer after a hardware change, you might see an error message that you have reached the maximum number of activations.
Generally, if you follow the transfer terms in the Software License Terms, you can move Office to a different computer, but you must activate it by phone and then uninstall Office from the original computer.
If you haven't installed Office on another computer yet, follow the instructions in Install Office on your PC or Mac.
https://support.office.com/en-us/article/download-and-install-or-reinstall-office-365-or-office-2019-on-a-pc-or-mac-4414eaaf-0478-48be-9c42-23adc4716658
Follow the steps to Activate by telephone, described below.
Uninstall Office from the original computer.
Considering your current scenario, just go to Step 2 and try activating by telephone.
Activate by telephone:
If you see the message Telephone activation is no longer supported for your product, you can ignore this error and call the numbers for your specific country/region listed in this article.
https://support.office.com/en-us/article/-telephone-activation-is-no-longer-supported-for-your-product-error-when-activating-office-9b016cd2-0811-4cb3-b896-5a6a13177713
In the Activation Wizard, select I want to activate the software by telephone and then select Next. If nothing happens when you select Next, use the Enter key on your keyboard.
Under Step 1 in the Activation Wizard, select your country/region, and then call the Product Activation Center phone number that’s listed under the country/region you selected.
When prompted by the Product Activation Center, provide the Installation ID that's shown in the Activation Wizard under Step 2.
The Product Activation Center will provide a Confirmation ID that you enter in the Activation Wizard under Step 3.
Select Next and follow the prompts to complete the activation process. If nothing happens when you select Next, use the Enter key on your keyboard.
If activation fails, see Troubleshoot activation errors.
https://support.office.com/en-us/article/unlicensed-product-and-activation-errors-in-office-0d23d3c0-c19c-4b2f-9845-5344fedc4380
In addition, read the Software License Terms to review terms on transferring Office:
Open an Office application, such as Word. (Here's how to find Office on your computer.)
Note: You can also view the Software License Terms online here: Software License Terms.
Go to File > Account > About program name (like About Excel) > View the Microsoft Software License Terms.
Terms for transferring ownership are located in the section: For Office 2019 and Office 2016, see section 3. Transfer to a Third Party
I hope this information helps you. If you have any questions, please do let me know and I'll be more than happy to assist you further with this.
Best Regards,
Michelle