Correct. Your license is good indefinitely. You only get one automatic transfer to a different flash drive per year, but should you have an issue before the year is up, you can email limetech and they will take care of you.
The license key file is tied to the physical drive, as long as you keep that key file, it's registered. Doesn't matter what you do to the rest of the files on the drive, format it, whatever, as long as you put the same key file back in the config folder, it's fine.
That may not have been the best move long term, physically larger drives seem to last longer. It would have been better to get a cable to mount the USB inside the case and attach to the motherboard's IDC header.
Something like this or similar. https://www.newegg.com/startech-usbmbadapt-usb-a-female-to-usb-motherboard-4-pin-header/p/N82E16812200294