When your contract term expires you will ‘roll-over’ to a monthly subscription.
You’ll be paying the same amount each month, but you’re out of contract so you can leave at any time. You’ll need to give your provider 30 days notice before leaving, so it’s best to plan a switch ahead of time.
If your contract included a phone, rolling over means you’ll keep paying for it when you don’t have to. Switching to SIM-only when your old contract ends lets you keep your old phone and pay less money each month. You can even keep your old number.