You can also submit the
Washington Arms Collectors online membership form then just go to the short line at one of the shows and provide payment and show your ID. Or you can use the
printer friendly version, send payment and copies of ID, then pick up your sticker for next year in the short line. There are selections there for "renewal" "address change" and "new membership" at the top of the forms.
There is also contact information on the main page,
www.washingtonarmscollectors.org/, if you have other questions.
It's pretty open as to when you renew. You can renew now for next season to get it out of the way if you wish, or just wait until you go to a show next season. If expired you just have to pay the non-membership entry fee, then they deduct it from your membership renewal if you go straight to the renewal area and provide your ticket stub.
At least, that's how I remember it.