So if you have Amex Plat, why would you get the PC membership?
AMEX Plat doesn't get you into alliance lounges (with a PC membership you can access the TLV lounge for example if you wanted) and generally only works with the airline you're traveling on.
I saw how the lifetime memberships went up from $250 in 1990 to $1,000 in 2,000 to $2,500 about 5 years ago and decided to splurge.
The annual membership fees go up every year.
It's over $5,000 now so it seems to have made sense. Plus I'm guessing when they merge with United they'll stop selling the lifetime membership. NW sold lifetime memberships before the DL merger and now they no longer sell them.
AMEX Plat has gone up from $300/year to $450/year since then as well.
Of course I didn't realize back then that they would let you in with a canceled AMEX Plat...