Hi,
In general if you have a volume license for Office 2019, then you can install the product on as many computers, as specified in your volume license.
If you are using the Office 2019 product that comes as a key or a box, you can use that on one computer only.
You can reach more experts and ask them over at the dedicated Microsoft Office forum over here:
https://social.technet.microsoft.com/Forums/en-US/home?forum=Office2016ITPro
(Please don't forget to accept helpful replies as answer)
Best regards,
Leon