CASE 1: You (or someone else) are using more than $this.View.AuthResponse.DeviceLimit devices and/or browsers at the same time → Log out of devices and/or browsers you don't use
CASE N°2: You are browsing in private mode →Log out systematically before closing the browser window
CASE N°3: You refuse connection cookies in your browser settings (or an update has modified your settings) → Change your browser's cookie acceptance settings
IN ANY CASE → clicking "continue on this device" solves the problem
What happens if I click "continue on this device"? You will be able to enjoy your account on this device and all your other devices will be signed out. You can always reconnect to it, within the limit of $this.View.AuthResponse.DeviceLimit devices.
How can I see the connected devices? Go to your customer area and click on "manage devices". If you go there after clicking "Continue on this device", there should only be one.