I've been invited to around 40 marathons, 1/2s and shorter (kinda a road whore) and I can only recall registering with an "elite" code a couple time. A few times I signed a waiver when I got to the host hotel and it seems like most of the time I never signed up or signed anything beyond providing a running resume. I don't recall signing up as invited for the 25k riverbank run either though it has been a few years?