Papal keys, vintage Catholic Sticker.
The symbol of the key is mentioned frequently in the Bible, especially in Matthew 16:19:
They are a symbol of the power that Christ gave to Saint Peter and his successors,
“I will give you the keys of the kingdom of heaven. Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven,” said Jesus giving the keys to heaven’s gates to St. Peter the Apostle
The crown traditionally symbolises; sovereignty over the Papal States, superior spiritual authority over civil power and superiority of papal religious authority over that of non-religious monarchs.
The three tiered crown can sometimes also represent the Pope’s powers as priest, ruler and teacher.