Microsoft 365 has victimized my software

It looks like you have several options:

• Transfer your copy of Office from your MacBook Air to your MacBook Pro – assuming that Microsoft will let you, and that the software is compatible. This will mean giving up the ability to use it on your MacBook Pro. You may need to contact Microsoft Support, or search for Microsoft Support articles, to find out how to do this.
• Give in and pay Microsoft for a subscription – maybe by upgrading your husband's subscription to a Family one that would cover you as well as him.
• Switch to other applications – such as Apple's (Pages, Numbers, Keynote), or LibreOffice . LibreOffice is free – although the developers will accept donations – and runs on multiple platforms, including Macs, Windows PCs, and Linux PCs.
• Use the Web version of Office (Microsoft – Microsoft 365 – Use Microsoft 365 apps for free on the web). You would be running the applications in a Web browser, not natively on your computer, so you could only use them when connected to the Internet. I don't know how performance and features would compare to the ones of the desktop versions. But for now, use of the Web apps is "free."

Long ago, I bought a copy of Microsoft Office for one of my Macs. It came with three keys, and you could use it on up to three Macs. I am not certain, but I think the rules may have allowed running all three copies at the same time.

These days, Microsoft seems to favor a "subscription" (rental) model, like the one that Adobe uses for virtually all of their software. You can still get a one-time purchase version of Office, but it is restricted to "1 PC or Mac."

Microsoft – Microsoft 365 – Compare All Microsoft 365 Plans (Formerly Office 365)

Microsoft Support – Transfer your Office license to another device or another person

"You can install a one-time purchase of Office such as Office Home & Business, Office Home & Student, or Office Professional Office on only 1 PC or Mac. However, you may transfer Office 2021, 2019, or 2016 to another computer that belongs to you, but not more than one time every 90 days (except due to hardware failure, in which case you may transfer sooner).

Any time you transfer the software to a new computer, you must remove the software from the prior computer and you may not retain any copies."

I am not certain, but I would guess that Microsoft is using DRM to keep you from having a working copies of Office on the MacBook Pro and on the MacBook Air at the same time. By limiting the one-time purchase version of Office to "1 PC or Mac", while they tie a Personal subscription ito "1 person" and the Family one to "1 to 6 people", they are trying to get you to choose a subscription over a one-time purchase.