again, i'll say, what exactly is a Lifetime Membership supposed to do?
you can just renew forever and be a lifetime member now
i guess lack could allow you to pay based on your age for a forever membership
lifetime expectancy based on country of residence and sex - current age X yearly membership price (maybe he can knock off a few years if you send him a pic of you smoking or working in a coal mine)
if the point is to show that you are somehow a super-duper member, than paying some cutthroat price for a unlimited membership doesn't do much in my opinion, and just opens up the possibility of people reselling the thing when they quit; but if you want to show your gratitude, go ahead and pre-pay for life, that would mean something.
maybe like a university or hospital, lack will name a sub-forum or territory on a map after you
