Suspense in a memoir is a fiction technique that can be used effectively to add both interest for the reader during the reading of the story and to pull the reader along to the end of the memoir.
Every successful memoir has to be mindful of not only edifying the reader but with entertaining the reader sufficiently to continue reading to the end. A memoir that fails to entertain is perhaps also a memoir that has failed to edify as the reader will not read the book in its entirety
While foreshadowing suggests something is about to happen, suspense is more focused on describing what is happening with the suggestion of dire consequences or of indescribably wonderful results.
If the story had to do with climbing a rockface, you would describe the distance between rock footholds and perhaps how narrow they were and then you would make allusions to how high you are and how injured you would be if you fell.
Suspense builds excitement and tension.
Obviously not every part of a memoir can be chock full of suspense, but a judicious use of suspense now and then can perk up a memoir.
A memoirist is encouraged to make use of fiction techniques, but the writer must never delve into fiction. If you are climbing a 15-foot cliff with plenty of vegetation to grab hold of, you cannot for the sake of suspense graduate the cliff into Yosemite’s El Capitan! Doing so is fiction, and fiction is not allowed in a memoir—but the use of suspense in a memoir is.
People will sometimes suppose that only big drama can make an interesting memoir. Of course, there are many readers who require constant titillation if they are to remain reading. Perhaps they are not the readers you should be seeking for your memoir. Nonetheless, nearly all readers require some attention to “interesting.”
No, I do not believe that it is the scope of the drama of your memoir that is the crucial element to creating interest. Some would-be memoir-writers get discouraged by the ordinariness of their lives. Yet, I have found that almost everyone I have had a serious conversation with about memoir writing had enough happen in their lives to fashion an interesting memoir.
An interesting memoir: drama vs. dramatic story development?
Much more important than the inherent drama of an action is the dramatic development of your story.