Can anyone please explain how Concierge TATL upgrade benefit expiration works?

I qualified for Concierge last year with that status expiring in November 2023
I have now qualified for Concierge again this year, with status expiring November 2024

I have not used any of my upgrades or companion tickets. Does this mean I now have 4+4=8 upgrades, 4 of which need to be used before November 2023 and 4 to be used by November 2024?

Similarly, do they need to be used on flights *flown* by the expiration date, or merely *booked* before the expiration date (i.e. the flight itself could be after the expiration date)?

Hope someone can help. I know I could ask the Concierge email, but I find their responses to these kinds of questions are often vague, plus I'd also like to understand what people's real world experience with upgrade expiration has been.

Thanks all