How about a personalized book?
You can write your own story about your relationship and your journey together, and have it professionally printed and bound into a book. If you're not confident in your writing skills, there are plenty of online services and companies that can help you turn your ideas and memories into a beautiful and meaningful book that your boyfriend will treasure.
You could also consider buying him a book of short stories or a novel by one of his favorite authors as a way to celebrate his love for storytelling. Alternatively, you could book a private storytelling session or class for you and your boyfriend to attend together, learning about the art of storytelling and spending quality time together.
Or you can get him a star map with the date of your anniversary.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.