Deleted microsoft office

Hello,
I had problems with my HP laptop every time I updated.
So, after 18 mths of restoring to an earlier date after each update, I decided to restore the laptop to the manufactory settings, but I did not back up as there was almost nothing on my computer.
But I forgotten that I had Microsoft Office witch I purchased last year and I cannot find the box with the product key.
When I purchased this Office it came with licence for 3 units.
So, I still have it on my husbands laptop.
Is there anything I can do?
On my husband's laptop, can I back up only the office and then restore it on mine?
Or if the laptop has an recovery D could I find it there and could restore only office?
Or could I find the product key on my husband's laptop?
Please help!!!!!!!!!!!!!