For all of you guys thinking of getting into the FCT by buying a refundable first class ticket/a different ticket for the same day/etc... DON'T DO IT.
The FCT is not a normal lounge; they cater exclusively to first class passengers, and as such, they provide a first class level of service. And part of that includes paying a LOT of attention to your ticket(s)/itinerary, to make sure that things work out for you, you don't miss any connections, etc. So if you play any sort of shtick like buying a refundable ticket, or a separate ticket from the one you actually plan on flying on, etc. they will catch on to your little game in about 10 seconds (or less). And even if they can't/don't/won't actually stop you, the potential for chillul Hashem is still HUGE - they will still KNOW that you are abusing the system. (As opposed to an "ordinary" lounge, where nobody pays attention to you once you're inside, and thus you can change or cancel your ticket freely without anybody noticing or caring.)