fdCal was made for free by mixin.com. No money is required to use the services, but it would be very generous of you to donate a few dollars to help pay for server costs, domain registration, and motivation for mixin company to continue to make neat websites like fbCal.
If you have desired Facebook applications, or modifications to fdCal, that you'd like to request, sending the request along with a donation :-) will get my attention.