The saints present our prayers to God. See Revelations.
See John 15:16
Also, in Rev. 5:8 , the prayers of the saints are likened to odours, and stored in golden vials.
Rev. 8:3&4 show an angel offering incense with the prayers of the saints up before God.
Do you save emails, texts, letters, etc? God saves it all. Do you ever go back and read those things? God does.
The saints are, living or dead, those sanctified by the Spirit of God: Acts 20:32; 26:18; Rom. 15:16; 1Cor. 1:2; 6:11; Jude 1.