Apple has changed the way iPhones/iPads identify themselves on iOS 7. Each device has a unique ID, which Studiometry uses to save registration and syncing settings.
The changes made in the new operating system will cause Studiometry to report that your Studiometry Touch serial number is not registered to a device that it should be, but there is an easy fix:
1. In Studiometry on the machine you use to sync with Studiometry Touch, go to the Preferences Window > Studiometry Touch section
2. Double-click on the "old" device that is shown as registered in the list of devices, and in the window that appears press the Unpair button in the bottom-right, and then press it again to confirm. This will from up your license from the old, pre iOS 7 device ID.
3. You can now sync from your Studiometry Touch device. When asked for a serial number simply enter the same one you had from before. Please note that if you changed any of the syncing/data settings for the device, you will also need to update those settings again, as it is identifying itself as a different device from before and the settings will not cross over.