(say for more than two weeks), you are requested to register it. The registration fee is not much, about what you would pay for a decent meal in a respectable restaurant (no, McDonald's does not qualify :-). Basically, the registration fee is:
$10 for this program alone, or
$15 for both this program and The Juker
You can use whatever method of payment you like. Inside the US, probably the easiest way for you is via a personal check or money order. Outside the US, you can just send cash.
Wrap the cash in a piece of paper or use a thick envelope, so that it won't be stolen.
You don't have to use US dollars, use whatever its equivalent of your currency
I might just keep it as a collectable.
Make the registration fee payable to M. Saggaf, and send it to this address:
M. Saggaf
262 Sidney St. Apt. #3
Cambridge, MA 02139
U.S.A.
email: alsaggaf@mit.edu
If you access to ftp, The latest version of the program should be available by ftp at