IOScope has been replaced by SignalScope Pro 2018 and the Pro Tool Set subscription in SignalScope X. If you already purchased IOScope, you may continue to use it. If you need to re-download it, you may do so for free. Please visit Apple's support site for instructions on how to re-download previously-purchased apps:
Subscriptions: Continuous Access to the Latest Tools and Features, Free to Try
You can download SignalScope X and for free. Some functionality is free to use indefinitely. For access to more powerful tools and additional features, a subscription is required. You can try a subscription for free for up to 7 days.
The 2020 versions of SignalScope will receive upgrades consistent with the respective subscription levels in SignalScope X through 2021. After that, they will continue to receive maintenance updates for a limited time and will continue to work indefinitely on compatible versions of iOS.