Shares passed 4200p but closed 0.2 per cent, or 10p, up at 4135p – taking gains under boss Erik Engstrom to nearly 800 per cent since 2009.
Luff said demand was growing among lawyers, scientists and medical professionals, while bankers need AI tools to fight financial crime.
The data and publishing group hiked its full-year dividend 7 per cent to 63p a share – worth £1.2billion to shareholders – and returned £1billion through share buybacks.
Relx also owns medical journal The Lancet and an exhibitions arm, which runs the comic book convention Comic Con.
Relx shares hit a record high after a surge in profits thanks to growing demand for its AI-powered products.
