Computer\HKEY_CURRENT_USER\Software\Nitro\Pro\12\Settings
For older versions of Nitro Pro (v12 and earlier), the serial number might be stored in the Windows Registry. how to find my nitro pro serial number
What are you currently trying to activate? how to find my nitro pro serial number
If you purchased a physical copy of Nitro Pro on a CD or DVD, your serial number will be printed directly on the packaging. This remains a reliable method even if you no longer have the software installed. how to find my nitro pro serial number
The most reliable way to find your serial number is to search the email inbox used for the purchase.