His mother Kelly Ellitts said the night of his murder just yards from their Wolverhampton home will always "haunt" her.
Brian Sasa, 20, Nehemie Tampwo, 20, Zenay Pennant-Phillips, 19, and Tyrique King, 20, were all found guilty of murder in January after a 13-week trial at Wolverhampton Crown Court. They were sentenced to life in prison at Wolverhampton Crown Court on Friday with minimum terms of 18 and 17 years.
Ms Ellitts, along with Keelan's father and stepfather, told Wolverhampton Crown Court how the youngster was cherished by his family and had his whole life ahead of him.
Ms Ellitts recalled how she saw the flashing of ambulance lights in Strathfield Walk, in the Merry Hill area of the city, on the night of May 29, 2018.
She recalled hearing her son's name being called and running towards the ambulances in panic.
"Whilst I was running towards the scene, people were saying it was not Keelan," she said.
"As I got closer to the scene, I recognised an item of clothing, then I knew it was Keelan.
"I saw stabs wounds all over his body. Whilst I was screaming, somebody was holding me.
"I don't know who it was at this moment. I didn't know Keelan had passed away.
"He was fit, strong and healthy. We were going on holiday in nine days time."
She described how she travelled in a different ambulance to hospital where doctors gave her the devastating news her son's life was over.
Ms Ellitts added: "Tuesday, May 29, 2018. That is the night that will haunt me for the rest of my existence.
"My first-born child was taken away from me in a horrific way.
"My world will never be the same. I know there is no light at the end of the tunnel. My 15-year-old baby is never returning to me. He is never going to settle down, get married and have children. Everything was taken away. How do you live with that?"
She said Keelan had plans to go to university and study architecture.
She remembered his "infectious smile" and the close mother and son bond which they shared.
Father Gary Wilson added: "Keelan was my first-born son. We had a close father and son relationship, enjoying things a father and son should. This has been taken away from me.
"All the things a father and son should enjoy throughout their lives has gone. All those precious moments Keelan and I should have spent together has been taken away.
"I remember the night Keelan was murdered. Kelly called me saying my son had been stabbed.
"I don't recall what my thoughts were at that time other than I had to get to the hospital.
"Kelly was distraught. I had never heard her like that before. I walked into hospital, gave my name and the receptionist told me she was going to call someone.
"I walked through some double doors and the nurse asked me 'have you been told what has happened?' Before I could answer, Kelly told me he was dead.
"There are no words to describe how I felt. None. I don't think I could describe how I felt. I went into the room and found that my son was dead.
"When I close my eyes, that is the image I see. The murder of Keelan affected my mother. She passed not seeing justice for Keelan. It affected my daughter."
Michael Ferguson, Keelan's stepfather, added: "Meeting Keelan was what I felt like at that stage.
"I was excited about everything, excited to leave school, excited for independence and especially to learn how to drive.
"I thought I could be anything. That is what I thought of Keelan.
"He had his whole life ahead of him. There are two things that will never leave me for as long as I love.
"That is watching the birth of my children and the other is watching Keelan's lifeless body."