IsUsageCodeValid
function IsUsageCodeValid (const Key : TKey; const Code : TCode) : Boolean;

IsUsageCodeValid returns true if Code is a valid usage code, otherwise false.

Key must be the same key that was used to create the code or the code is considered invalid.

This routine is defined in the OnGuard unit. (as of 1.15 this routine has been moved to the OgUtil unit)