This statement indicates that the final outcome and the complete story will be known and shared by those who stay through the entire process. It might also suggest that the story is something that unfolds over time and only becomes clear to those who are there until the end.
Basically, it suggests that only those who endure to the conclusion have the right or ability to convey the full story. It could imply that the journey or event is complex and only the ones who complete it truly understand and can communicate it accurately.