[macOS, Windows, iOS] 50% off Freedom Lifetime Subscription US$64.50 (~A$85.20) @ Freedom.io

Freedom is a highly rated distraction blocker for both your computer and your mobile devices, which you can use to block distracting websites and apps that will kill your productivity.

Syncs across devices. Choose to block your apps, websites, internet access. Schedule focus times.

Lifetime subscription at 50% this mouth with code JUN2021

There's also a free trial - Your trial includes 7 sessions on unlimited devices.
Scheduling and Locked mode are premium features.