Memento is mainly about a man who has a short term memory and uses pictures and notes in order for him to know who is around him. In order for this man to capture his wife killer, he tattoo evidence of this on his body. This is a psychological thriller. In a psychological thriller, suspense is often created by two or more characters preying upon one another's minds, or either playing mind games like cat and mouse.
There are many type of suspense in memento. In one scene that shows suspense is when he talking to on the phone to someone for a long time and then questions who he is talking to on the phone. In this part the uses of sound helps to build up the suspense. The music stops just before he asks who he is talking to. When the music stop it grabs the audience attention and makes them think that something is happening.
In beginning we see the main character shooting one of the other characters in the head. By having this happen at the beginning of the film it builds suspense and leave the audience clueless and wanting the audience to carry on watching.
Suspense was also created through flashbacks. Each flashback held the answer or showed a vital clue to the story. The flashbacks created suspense because they kept going back to crucial points in the story, though at the time you're not sure why they are so important.