Never called them anything but tabs. Stickers like animal stickers or temporary tattoos or something? Talked about in a different discussion but back in the 50’s or so when they first came out with keeping your plate for a few years instead of getting a new plate every year, they were actually embossed metal tags with a tab that fit into a slot in the license plate. Then they were secured with a bolt. Usually a stove bolt back then. So that might be where the term tabs came from. They actually had a tab that fit the slot. Took all the fun out of collecting license plates. In Minnesota anyway.