I know we already have the yearly sticker, but is there enough interest for one that goes inside the car facing out. Maybe they could be like your tax disc holder (or maybe even be a tax disc holder?) and not be sticky but rely on a lick!
Another thought, maybe a Club Arnage 'GB 'or 'NL' plate that could go in the rear window.
I thought that maybe it would not feature a year but just the Club Arnage Logo. This could then stay on year round.