Oliver Tree's Celebration of Life

Oliver Tree's friends and family laid the star to rest Saturday evening during a celebration of his life.

Logan Paul, Diplo, Ethan Klein, Aaron Mercury and more of Oliver's loved ones spoke during the memorial service.

Oliver died in a helicopter crash last month when his craft collided with another in Brazil. Oliver was one of six people who were killed.

An art foundation dedicated to his memory was launched after his passing ... and stars like Post Malone paid tribute to him.

Fans have already shown the star love ... including at Venice Beach late last month in honor of what would've been his 33rd birthday.