The original version of SignalScope Pro, which was available in the App Store soon after its opening in 2008, has been replaced by new subscription-based and perpetual license apps. If you purchased the legacy version of SignalScope Pro, 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.