Princeton Airport lounge searches usually turn up nothing because there is nothing to find: Princeton Airport (PCT) is a general aviation field serving flight training, charter, and private aircraft in central New Jersey, not a commercial terminal with scheduled airline service, so it has no lounge of any kind, whatever specific membership prompted the search.
That absence is really a byproduct of what kind of airport this is. Fields built around instruction and private flying do not carry the passenger volume that makes a lounge worth building, and Princeton has never added one, because the flying done here rarely involves the kind of connecting, ticketed passenger that a lounge is designed for, and that has been true throughout the field's history.
If you are near Princeton and actually need lounge access, the realistic options sit an hour or so away at two much larger airports. Newark Liberty International Airport, one of the New York region's three major hubs, carries a full range of airline and membership lounges built for the volume of international and premium traffic it handles. Philadelphia International Airport, similarly, is a full-service hub with its own lounge network serving domestic and international connections. Either is a far more realistic target than Princeton if a lounge is part of your travel plan.
For travelers actually flying out of Princeton itself, whether for training, charter, or general aviation business, the practical picture is a small general aviation terminal with basic amenities rather than anything resembling a passenger lounge. Arrange ground transport and any waiting around your flight instructor's or operator's schedule rather than an airport facility, and if your itinerary connects onward through a commercial flight, build your lounge expectations around Newark or Philadelphia rather than Princeton, since nothing at this field will change that picture regardless of which airline or membership program you hold.