Did you copy license file from 2020 to 2024 folder? It’s located in \AppData\Roaming\Microsoft Flight Simulator\Packages\justflight-aircraft-146\work\userinfo.txt for Steam version.
I can see there is an extra “Community” folder in Packages location so the new path should look like this:
\AppData\Roaming\Microsoft Flight Simulator 2024\Packages\Community\justflight-aircraft-146\work\userinfo.txt
Of course this is an example for their BAe 146. I can’t guarantee it will work but it’s probably your only option before JF releases installation files for 2024.