GetSerialNumberCodeValue
function GetSerialNumberCodeValue (const Key : TKey; const Code : TCode) : LongInt;
GetSerialNumberCodeValue returns the serial number that was used to create the Code.
Key must be the same key that was used to create the code or the code is considered invalid. If the code is invalid, 0 is returned.
This routine is defined in the OnGuard unit. (as of 1.15 this routine has been moved to the OgUtil unit)