Memoir For Grandfather

My family and I are looking to have a memoir written for my grandfather …he’s getting up there in age and we would like to preserve his stories, life accomplishments as told by him while his mind is still sharp. He has quite the stories from his military days, as well as working for the mayor of Chicago in the late 70s / early 80s. Project would entail sitting with him across a few sessions to gather the most meaningful stories, experiences, etc. and then draft a memoir.