A great idea could be a How I Met Your Mother merchandise, such as a T-shirt with his favorite character or quote from the show, or a coffee mug with a similar design. You could also get him the complete series of the show on DVD, so he could watch his favorite episodes whenever he wants. Additionally, you could consider booking a trip to New York City, so he can visit some of the show's famous landmarks, like MacLaren's Pub, and relive his favorite moments from the show in person.
Or you can get him a star map with the date when he welcomed you in this world.
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.