Technically, the answer is 0. Conspiracies don't go into your deck; they are in your sideboard after drafting. Then, at the beginning of the game, you put any Conspiracy you drafted into your Command Zone. There is no limit to the number of each Conspiracy you can have in the Command Zone.
Since conspiracies are for Limited play only, there is no upper limit on the number of copies you can use in a game, just like there is no limit for any other card in Limited. You can use however many you can get your hands on through event means (drafting, getting packs for your Sealed pool).
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)