Sir Paul McCartney has said his concerts are a way of helping him "revisit" other Beatles members and his late wife Linda.
Launching his new live CD and DVD in London, the singer admitted he could get "emotional" on stage.
"If I'm doing songs by The Beatles, I obviously remember the sessions when we recorded," Sir Paul said.
"There's a song I do called Here Today which is specifically written for John, and that sometime catches me out."
Sir Paul will embark on his first European tour for five years in December.
The tour opens on 2 December in Hamburg, where the Beatles honed their sound with live performances in clubs between 1960 and 1962.
It concludes at London's O2 Arena on 22 December.
Sir Paul's live release, Good Evening New York City, was recorded during his concerts in New York's Citi Field, formerly the site of the Shea Stadium where The Beatles played to a record-breaking audience in 1965.