This concern was addressed via email. The response is posted here for everyone's benefit:
If you purchased SignalSuite from the App Store, you can still re-download it using the same App Store account with which you originally purchased it. Here is a link to Apple's instructions for redownloading apps: https://support.apple.com/en-us/102417
If the app is already installed on the device, but gives an error when trying to open it (e.g. "This app is no longer shared with you."), you may need to delete the app from your device before re-downloading it from your App Store account. It may help to reboot the device after deleting the app, before re-downloading.
