Does your customized lanyard need this breakaway buckle? Yes, it is for safety
The Lanyard Safety Breakaway prevents the wearer from being choked or strangled by the lanyard. It is generally stitched in the back of the lanyard and is designed to come loose when a lanyard is snagged or pulled on with force, thus this is a highly recommended add-on.
Buckle is the most recommended as in you can removing your belonging by release the buckle without takeout from your neck.