In my Steinberg UR44, I got an e-license and the manual warns you NOT to lose it, as effectively, that's what you bought, according to Steinberg... the interface was free, you just bought the little USB thingie that lights up.
If I don't have it inserted, whenever I fire up X3, it asks me where my Steinberg effects are (that are in the interface), so I just let it live in a USB port now. I prefer the auth/registration setup best, but this seems to work ok. It allows for using on other machines, apparently as the reasoning behind this method