At any event with more than a handful of people, identification becomes a practical problem. Who is a delegate? Who is a speaker? Who is staff or crew? Who can access a restricted area? Custom lanyards with ID badges attached solve that problem without requiring anyone to check a list.
But beyond the functional purpose, a lanyard is also a branding surface. Every delegate at a conference wears your organisation name or event brand around their neck for the duration of the event. At a two-day conference at ICC Belfast or a trade show at Eikon Exhibition Centre, that is consistent brand exposure across hundreds of people in a room where everyone is paying attention.