IMTU, I would run it like a cross between some of the airline lounges, the Seafarer's Club, and other "private" clubs worldwide. In that, the TAS member could sign in a guest(s) to the lounge, get them (limited) access to some of the dining and online resources, BUT they wouldn't have full privileges such as an overnight stay, a shower, or "members only" job listings. Given the billions of sophists in the galaxy, and the resulting number of TAS members and associates, the organization will turn somewhat of a blind eye towards a member or two of a group lining up a patron under these auspices. Similarly however, TAS expects such groups to treat the hostel as a more or less "neutral ground" and avoid shenanigans on-site.
Which now has the TAS working as variations of "The Cosmopolitan" from John Wick bouncing in my brain. And yes, I recall at least one poster here has done a motif of TAS as a grand secret society already...