So many beautiful songs have been written over many years and there is no record of them. Some songwriters are happy just to write a song with memorable lyrics and a beautiful melody. A song is never complete until it is noted somewhere.
It can be scored on music sheet, or recorded as audio in a studio or simply by connecting your keyboard to a computer and playing into the music software that is available.
Learn to accompany your song on piano and record it in some form. You can sing while you play and it will be there when you or anyone else needs it. In the future it may be useful for some bigger project. Someone may find your song just right for a production in the future, and you will have evidence of ownership.
There are so many outlets for earning an income from original music. You can have your song licensed to a music library, A music library provides instrumental and vocal music for all the many movies, advertisements, and special occasions. Many musicians shy away from this outlet because they feel their music is too simple and that role is only taken up by big composers. Haven’t you heard some of those simple jingles on television ? It doesn’t take much to arrange them. So why not dust off those compositions, record and earn from them ? Can you imagine the pride you would feel hearing your little song on the radio?