Just to keep you in my heart forever. Mainly refers to this you, left a very deep impression on me, so I can't forget it. This sentence must have a premise, that is, what I have done to keep you in my heart.
The original words of this sentence are from the Mongolian song "Draw You" sung by Korqinfu. The lyrics of the whole sentence are "paint your beautiful image on the top of my hometown, freeze your sweet smile in my heart, and describe your beauty with your affectionate singing, just to keep you in my heart forever". In this song, you mean the lover of the singer, so if you quote this sentence, it is for the person you love.