You purchased PokerTracker 4 on 5th April so any hands you imported during your trial should still be there provided you didn't uninstall anything in between your trial and purchasing PokerTracker 4 (or change computers). Also any hands played between the trial and purchasing can be imported provided you have them. If you need to reimport hands from your trial period you can do so using 'Play Poker -> Get Hands From Disk' and then navigating to your 'Processed' folder provided the hands were originally played on your current computer:
C:\Users\{Windows Login}\AppData\Local\PokerTracker 4\Processed
Guide: Processed FilesIf you do not see the AppData folder in Windows File Explorer then please refer to
this guide.