In flat netting, a Stop Bead is required to hold the initial row in place on the thread and also helps with keeping the correct tension as the work grows.
For Circular Netting, you don’t necessarily need to use a stop bead. If you struggle with keeping your tension uniform you can optionally use a stop bead for circular or tubular work as well.
Check out this Post if you need a refresher or have not used a stop bead before.