NadirSyedwas arrested hours after buying a chef's knife in November 2014, days before Remembrance Sunday - held on the second Sunday of November to commemoratethe contribution of British and Commonwealth soldiers in the two World Wars.
The judge said Syed must serve at least 15 years but he may never be released.
During his trial last year, Woolwich Crown Court heard how the 22-year-old from Southall area of west London had been inspired by ISIS leaders urging attacks on Western targets, including police and soldiers.
"I have no doubt that he is dangerous. In my judgement if he was released from prison he would go and try and carry out what he failed to achieve in this case. He would set out to kill in furtherance of his beliefs," he ruled during sentencing today.
Prosecutor Max Hill had said Syed was actively searching for knives of "sufficient quality to source an attack".
The prosecution said the fatwa that inspired Nadir Syed urged followers to rise up against westerners and "rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads."
"This fatwa, and the worldwide attacks that followed, inspired the defendant to plan his own attack in this country, emulating the attack on Lee Rigby carried out by Michael Adebolajo, who he considered to be a mujahid or Islamic fighter," Hill said.
Syedhad also tried to travel to Syria to fight with ISIS militants but had been stopped from leaving the country in January 2014, it emerged in court.
