[conan981]

i just want to add a little hint, since i had to play with this protection time ago.
to generate valid keys, we need all the data described in posts above(PRIMARY KEY AND MODIFIER/S) AND
to know what type of keys we need to generate. (to generate keys we can use demo generator adding our keys and modifier)
To know that info, we can check into our app what function is called among

ISDATECODEVALID
ISDAYSCODEVALID
ISREGCODEVALID
ISSERIALNUMBERCODEVALID
ISSPECIALCODEVALID
ISUSAGECODEVALID

every function using mixblock function extract from our serial a constant that is checked

const
{magic values}
DaysCheckCode = Word($649B);
DateCheckCode = Word($A4CB);
NetCheckCode = Word($9341);
RegCheckCode = Word($D9F6);
SerialCheckCode = Word($3C69);
UsageCheckCode = Word($F3D5);
SpecialCheckCode = Word($9C5B);