The first known use of plenary indulgences was in 1095 when Pope Urban II remitted all penance of persons who participated in the crusades and who confessed their sins. Later, the indulgences were also offered to those who couldn't go on the Crusades but offered cash contributions to the effort instead.

Who created plenary indulgence?

The earliest record of a plenary indulgence was Pope Urban II's declaration at the Council of Clermont (1095) that he remitted all penance incurred by crusaders who had confessed their sins in the Sacrament of Penance, considering participation in the crusade equivalent to a complete penance.

When did indulgences start and end?

While reasserting the place of indulgences in the salvific process, the Council of Trent condemned “all base gain for securing indulgences” in 1563, and Pope Pius V abolished the sale of indulgences in 1567.