Aura uses Apple's Screen Time controls to block apps. If Screen Time is turned off, Aura loses the permission it needs to hold those blocks.
You can add a Screen Time passcode in iOS Settings, Screen Time, then Lock Screen Time Settings.
The useful part is not knowing the code. Ask a partner or friend to set it, or generate a random code and keep it somewhere inconvenient to reach.
Apple may let you reset a forgotten code with your Apple Account. That is still an escape hatch, but it adds enough friction to stop an impulsive override.
This passcode belongs to iOS. Aura cannot see, store, or reset it.