If you cancel your subscription, you will be logged out, and will not be able to log in again until you re-subscribe. Even if your subscription ends, Arcade will play any MIDI data sent to it, and any old sessions will sound exactly as they were left. Whatever work you do while subscribed is yours to keep forever. You will simply not be able to access the interface or make any new tweaks to the work you've done with ARCADE.
If you'd like to re-subscribe, click here: https://output.com/account/subscriptions and choose the "Sign Up Again" option.