Complex sentence: Three months later on June 1, he met McLamore and formed the Burger King corporation, opened Burger King stores and went on to introduce the Whopper burger in 1957, when they also dropped Insta from the name.
Split into simpler sentences: Three months later on June 1, he met McLamore and they formed the Burger King corporation. It opened Burger King stores and went on to introduce the Whopper burger in 1957, when it also dropped Insta from the name.