Once you have unlocked the cheats below, you need to replay a Memory, then go to the Options menu, Cheats, and then select the cheat you want to use.

Unlock Ride the Unicorn cheat
Earn 100 percent total synch* in Sequence 1: Peace at Last.

Unlock Buns of Steel cheat
Earn 100 percent total synch on Sequence 2: A Wilderness of Tigers.

Unlock Killing Spree cheat
Earn 100 percent total synch on Sequence 3: The Fighter, the Lover and the Thief.

Unlock Sisterhood cheat
Earn 100 percent total synch on Sequence 4: Den of Thieves.

Unlock Ultimate Guild cheat
Earn 100 percent total synch on Sequence 5: The Banker.

Unlock Unlimited Assassin Signals cheat
Unlock 100 percent total synch on Sequence 6: The Baron de Valois.

Unlock Desmond Everywhere cheat
Unlock 100 percent total synch on Sequence 8.