Abdulmalik Adua, 17, of Woolwich and Rezwan Islam, 19, of Gloucester, were both sentenced to a minimum of 16 years in prison.
Paul Pass, 49, was stabbed in his flat in Gloucester last October by the pair, who used it as a drug-dealing base.
Adua and Islam were found guilty of murder at an earlier hearing. Islam was also found guilty of kidnap.
Bristol Crown Court heard Mr Pass was hit over the head with a guitar and stabbed in the leg, which caused his death.
Bilal Ebrahim Moosajee, 19, of Gloucester was jailed for nine years after admitting manslaughter and kidnap at an earlier hearing.
He will serve half his sentence before being considered for release on parole.
The court was told the men were all part of a drug-dealing gang from outside the county who were trying to establish themselves in the city.
They offered Mr Pass free drugs in exchange for using his flat as a base.
The gang took revenge by attacking Mr Pass after his friends had broken into the flat and stolen their drugs.
Mr Pass's mother Josephine said: "I feel both angry towards the men who took Paul from me and great sadness for their mothers.
"They have not only taken Paul's life, they have taken mine away as well because I feel like I have died."

Activists say about 35 pro-government fighters were killed and some medical staff taken hostage. More than 20 IS fighters were also reported killed.
The attack was centred on al-Assad hospital, to the west of the city.
Government forces retook the hospital after several hours, reports say, but the fate of the hostages is unclear.
BBC Arab Affairs Editor Sebastian Usher says the latest offensive shows that IS, despite recent setbacks, can still threaten significant government territory.
IS controls more than of half of Deir al-Zour and is seeking to capture the entire city.
The group has been besieging government-held areas there for two years, trapping about 200,000 civilians.
IS's Amaq news agency said its fighters had carried out a "major offensive" in Deir al-Zour early on Saturday, storming the hospital and cutting the route between a Syrian army base and the city's airport.
It said it had also taken over a fire station, university accommodation, grain silos and territory near the al-Tayyam oil fields.
A UK-based opposition news service, the Syrian Observatory for Human Rights, says government forces retook the hospital after several hours of fierce fighting.
Deir al-Zour is in an oil-rich area and on a vital supply route to the IS stronghold of Raqqa.

Barry Joy, 56 and Daniel Timbers, 28, died in a "fierce fire" following an explosion at digger bucket maker Harford Attachments in Norwich in 2015.
The coroner said Mr Timbers had been standing in for his father who was ill.
Post-mortem examinations said the men died as a result of the effects of fire and inhalation of fumes of combustion.
The inquest was told staff heard a "loud noise" at about 09:00 BST on 13 July 2015.
"Staff evacuated the premises, with some of them bravely trying to rescue Mr Timbers and Mr Joy," coroner Yvonne Blake told the Norwich inquest.
She added, "Their bodies were recovered from the booth afterwards."
Paint sprayer Mr Joy, of Spencer Street, Norwich and production operative Daniel Timbers, of Dereham Road, Norwich, were working in one of two booths bought from RAF Lyneham in Wiltshire when the base was closed down.
Kenneth Stedman, managing director of Ipswich-based Industrial Powder and Paint Services, advised Harford Attachments on the transaction.
The inquest heard the two units were "well kept for their age" and he advised the company that they would be suitable to be set up as they were on the airbase.
The coroner said the jury inquest, which is continuing, would hear evidence about training of staff, policies on site and extraction equipment on the paint-spraying booths.
Two teenage drug dealers who murdered a man in a revenge attack have been jailed.
[NEXT_CONCEPT]
Militants from the Islamic State (IS) group have briefly overrun a hospital complex in the eastern Syrian city of Deir al-Zour, reports say.
[NEXT_CONCEPT]
Two men who died in a paint-spraying booth were so badly burned they could only be identified using their dental records, an inquest has heard.