Limetech does not care what license is running on what server ; and has no way of verifying that.
The license is only attached to the GUID of the flashdrive. Not any other hardware.
As long as each server as it's license, you are fine.
It will read and or write the full surface of a drive how many time your program it and check that what is read is conform to what was written (zeros) and watch the SMART attributes for errors.
I think that SimonF has good results with the QNAP QNA-UC5G1T. Maybe others work too.
https://forums.unraid.net/topic/127515-solved-trying-to-add-usb-c-30-25gbps-ethernet-adapter/?do=findComment&comment=1162552
That's sound like a plan.
What is your current version of Unraid ? (I suppose that your signature is not up to date v6.2.4)
While #2 is running, I would say to read the release notes of major version between your Unraid and 6.10.3.