WINNER‘s “Have A Good Day” is a song written and composed by Mino, and all signs point to it being a memorial song for Ladies’ Code member and high school classmate EunB.
While it’s well-known that Mino and Block B‘s P.O. went to the same high school, EunB was indeed also their classmate. When she died in that tragic car accident, Mino showed the connection between the two when he listened to “I’m Fine Thank You” and appeared to post a message to her.
Mino explained the motivation for creating “Have A Good Day”, and it sounds a lot like EunB’s situation.
“Have A Good Day” is a song, for which I worked as the main producer, and it’s a memorial song. I made it a long time ago when a friend of mine left for the heaven due to a sudden accident, I made it with the heart of cherishing the memories about the friend.

Given that the Ladies’ Code accident happened in 2014, the timeline appears to match.