On Mon, 13 Aug 2018 18:47:35 -0500, swalker wrote:

Finally broke down and bought a new bare bones laptop that came with
Win 10.

One of the programs I must have is Outlook 10. Since I bought a copy
at Best Buy a few years back and have been using it on a couple of
computers I assumed installation would not be a problem.

Not so, MS says the Product Key I have isn't valid.


See: '"Copy", "Move" or "Transfer" an Office installation to another computer.'
https://answers.microsoft.com/en-us/msoffice/forum/msoffice_install-mso_other-msoversion_other/copy-move-or-transfer-an-office-installation-to/956244a0-385d-4e21-a21e-87b4179111d1

Two key points:
1) There are different types of licences. Your licence must be of a
type which allows you to "transfer" the license from one computer
to another. Some licences do, some don't.
2) If your licence allows transfer and Internet activation fails,
then you have to resort to a phone activation.


Do these things expire?
Is there some limit on the number of computers that can use a single
copy?


As others have already replied, yes there is a limit.


--
Kind regards
Ralph