Joseph Zulu, 23, stabbed Adam Watt, 38, outside his Hemel Hempstead home with such force the knife cut through bone in his upper chest.
St Albans Crown Court heard Watt had been punished “for running off”.
Another man, 18 year-old Nicholas Grant, was cleared of murder but convicted of manslaughter and jailed for 11 years.
The jury heard that Watt fled after meeting the two men to buy crack cocaine and heroin worth £10 on the evening of 7 January.
Zulu then called Grant and the two men confronted Watt outside his home in Evans Wharf, Aspley Lock, where he was fatally stabbed at around 01:10 GMT.
He died in hospital five hours later.
Judge Andrew Bright QC said: “Adam Watt was a customer of yours. The motive was to punish him for running off. You could not be seen to allow a customer to run off with drugs without paying for them.”
The jury found Zulu, of no fixed address, guilty of murdering the former chef, as well as conspiracy to supply Class A drugs. He will serve a minimum of 25 years.
Grant, of Sunnyhill Road, Hemel, also admitted conspiracy to supply Class A drugs and was sentenced to a total of 11 years.
Jacqueline Brewin, 47, of Sacombe Road, Hemel, who drove the two men to and from the area of the killing, was cleared of all charges.
Zulu, who was born in Zimbabwe to a father from Lebanon and mother from the Congo, came to the UK when he was 11 years old.
Prosecutor Rosina Cottage told the court that Zulu could now face deportation, however Hertfordshire Police confirmed he will serve his sentence in the UK first.
In a statement read to the jury, Alexander Watt said his son had been in a constant battle with drugs.
“Although Adam’s addiction ruled his life, it never erased his love for his family and his deep routed decency.”-bbc