You will need the full version of the software in order to recover files from the device. This is specified in the FAQ page. As you will see below, the developers explains the difference between trial and full version(registered) of the software.
All functions of trial version and registered version are the same. But the trial version has some limitations. For example, the unregistered FoneLab can scan your device and display files on your device, but cannot recover files. If you are a registered user, it can assist you to recover files without any limitation and you will be entitled to get free upgrade for lifetime and full technical support from us.
For more information, access the FAQ page: http://www.aiseesoft.com/iphone-data-recovery/faq.html