would only be a backup (.bak) anyway.
Yes, you can copy it over via flash drive.
Just paste it into the system32 folder.
Keep in mind, this is a database file, and has a record of the system hardware. At boot, Windows compares the system to this file, and this file is only good for the computer it was created on.
To do this properly, you should copy the wpa.dbl from the computer you are working on BEFORE you reinstall windows, then when you copy it back, you do not have to reactivate.
Hopefully, in this case, it will at least break you out of the activate now loop. You may still need to activate, or change the product key to the propper one.