DB, this was not an airline/alliance lounge. It was a company that sells access to airlines which don't have their own lounge, members of external clubs (Priority pass, etc) and all and sundry who are prepared to pay a fee.
Premium customers for said airlines are given a printed 'invitation'. Club members sign in and the all and sundry get out their credit cards.
Edelweiss, for example, flies to Vancouver in the Summer only, three and four times a week. Their business class passengers are invited to one of these lounges. (Although I would have expected them to use a Star Alliance partner's lounge)