Autobiography is a form of narrative dealing with the self- it tells one's life story or recounts important events and themes up to the time of writing. Because autobiography is self-written, most people are writing well before their life story has really come to a close! I think that this leaves you with an interesting choice when it comes to writing the ending of your autobiography...
Do you want the ending of your autobiography to present finality, continuity, or change?
For example, let's say an author working on their autobiography has had a long career as a chef. In ending their autobiography, they could imply a sense of finality by saying that they are retiring or closing their restaurant. This "closes the book" on the major theme of their career as a chef, and even though they may do other things in their retirement, this part of their life is over.
To present continuity, the chef might end their book by saying that they look forward to many more years working in their restaurant and do not plan to make any new changes. Perhaps their autobiography has recounted their rise to success, and now their life has entered a stage of stability.
Alternately, the chef might mention that they are opening a new restaurant, or are moving to another country to learn to cook foreign cuisine. This presents change in the story while opening up the possibility that their life story will continue to evolve.
How might the options of finality, continuity, and change relate to your personal autobiography? Consider whether you are ending a theme or "chapter" of your life, continuing in a theme, or making some changes. The most appropriate ending should reflect information already established in your autobiography, but tell the reader what they can expect to happen next- even if it is nothing at all!