Each club member is assigned a unique member number. You keep that number always. So if your membership lapses, and then you rejoin the club, you will have the same number.
Your member number is part of the filename when you submit to N4C contests. It may also be used to identify you in blind submissions, when needed for club activities. You will also use your member number if you choose to vote on the club's top submissions to monthly N4C contests.
New members will receive a member number soon after they join the club. If you have a question about your member number, contact one of club's N4C representatives.