Office 2019 suddenly lost activation after running for many months.

That strange because I am still using Office 2010 Professional on one of my computers with 10

How much of Office do you need because in case you do not know, and do not mind using online - Office online is free , but only word excel and powerpoint
You can create your docs and still store them on your local computer, as against just online. Needs a Microsoft account.

https://www.microsoft.com/en-gb/micr...ne-for-the-web.

I could not really advise on - should you purchase from the same supplier.

I have set up 10 for a friend who did not have office and have used Libre
How to Get Microsoft Office for Free

Landyman said:

I bought the other copy, because Microsoft would not register my old Office 2010 on a replacement laptop - said it was too old!

Alan,

I activated Office 2007 on a new computer only a few months ago. There should be no problem with your Office 2010 activating. What happened?

You had uninstalled the trial version that was probably bundled with your new computer first?
Otherwise your activation could have mistakenly been an attempt to activate that new bundled version using your old Office 2010 key - hence the failure.
- The existence of the bundled new version might have misrouted the activation request to be for that new Version.
- There have been reports of this before.

Personally, I'd uninstall all versions of Office then install just the Office 2010 I was interested in and try activation again.
Uninstall Office from a PC - Office Support
Manually uninstall Office, Apps - OfficeSupport


Best of luck,
Denis

Alan,

You might try the solution provided in
You maybe a victim of piracy Office 2019 - TenForums

Denis