I am sure that God cannot be manipulated. And God doesn’t need our prayers. We need our prayers.
When we pray the Memorare, or any other prayer, we are not trying to bend God to our will. We are trying, through our prayer and devotion, to bend ourselves to God’s will for our lives. We go to our Heavenly Father with childlike piety, knowing, as Mary did, that nothing is impossible to God.
That’s what prayer is all about.