Simplify the following text for a Grade 12 native English-speaking person.
Original: The companies that operate within it have for brand recognition purposes retained the famous Kirov name , acquired during the Soviet era to commemorate the assassinated Leningrad Communist Party leader , Sergey Kirov ( 1886 â `` 1934 ) .
Simplified: The companies that use it have kept the famous Kirov name , which it got during the Soviet period in honor of the murdered Leningrad Communist Party leader , Sergey Kirov ( 1886-1934 ) .