Hello,
Sorry to hear you are having issues. For Fences 5 you will need to purchase new license key. You Fences 3 key will not work on Fences 5. Your license key will still be valid for Fences 3. Fences 5 should pick up your layout from Fences 3.
Check updates in Fences will only show any new update for Fences 3 if any.
Thank you.
Basj,
Stardock Community Assistant.