At the Last Supper Jesus anticipated the free offering of his life
The Eucharist that Christ institutes at that moment will be the memorial of his sacrifice. Jesus includes the apostles in his own offering and bids them perpetuate it. By doing so, the Lord institutes his apostles as priests of the New Covenant: "For their sakes I sanctify myself, so that they also may be sanctified in truth."
Source: Catechism of the Catholic Church (Vatican.va)