If your module has a code on page 1, that's what you use.
If your module doesn't have a code, then it's an older product and pre-dates the program. Though new printings of older products will have a code, like how the new printing of Emerikol has a PDF code in the front...
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Gnome Boy • DCC playtester @ DDC 35 Feb '11. • Beta DL 2111, 7AM PT, 8 June 11. Playing RPGs since '77 • Quasi-occasional member of the Legion of 8th-Level Fighters.