Short answers, pulled from the story.
Charles IV, Holy Roman Emperor, founded the Order of the Golden Spur on the 15th of August 1357 in Prague. This specific date marked the beginning of what would become the Order of the Golden Spur.
Titian received the Order of the Golden Spur in 1533 after painting an equestrian portrait of the emperor. The order was granted to those in the pontifical government and artists whom the pope thought deserving of reward.
Grand Duke Jean of Luxembourg died on the 23rd of April 2019 at the age of ninety-eight and his passing marked the end of active membership within the Order of the Golden Spur. There are no living members of the order following his death and the order is now considered dormant by historians and Vatican officials alike.
Pope Pius X divided the order into two separate entities on the 7th of February 1905 during his motu proprio Multum ad excitandos. One part took the name of Order of St. Sylvester while the other retained the older name of the Order of the Golden Spur.
The order was given out liberally upon payment of a small fee which damaged its reputation significantly by the mid-18th century. Members of the Curia, prelates, and papal nuncios had the privilege of nominating recipients for decades.