Here's what the World Fact Book says:
"Aruba seceded from the Netherlands Antilles in 1986 and became a separate, autonomous member of the Kingdom of the Netherlands. Movement toward full independence was halted at Aruba's request in 1990."
Still, for location purposes (like shipping, postal addreses, etc etc) it goes by "Aruba"...sort of like how people use "Puerto Rico" rather than the United States if they live on that island.