A couple of years ago, my mother had to put down the dog I basically grew up with. He was 14, a border collie, the best dog in the world. He had a great personality, was gentle with us even when we were too rough, and made us laugh a lot. He slept on top of of the doghouse my father made for him, barked at thunderstorms, chased birds, and ran away from us when he got out of the back yard so he could watch us try to catch up. In his later years, he never left my mother's side, and she adored him. I'll never forget him, and my mom has a collage of pictures dedicated to Sgt. Pepper still hanging on her wall. He was my best friend growing up.
The best tribute to a friend who has moved on is to never forget.