Interesada literally translates to "interested," but in the context of this song, it carries a much stronger, negative connotation, meaning "self-interested" or even "gold-digger."
The song's title, "La Interesada," and the lyrics repeatedly describe a woman who is only with the singer for his money and possessions (like a Mercedes or vacations), rather than genuine love. It's a key word that encapsulates the entire theme of the song, making it both memorable and central to understanding the narrative.
Have you ever felt like someone was only with you for your money? In "La Interesada," the singer confronts this exact situation. He's realized his beautiful girlfriend doesn't truly love him. Instead, he feels she's only interested in his possessions, like his Mercedes. He calls her out for being "interesada," a Spanish word that describes someone who is materialistic and motivated by financial gain.
The singer feels used and warns any future partner that she will be very expensive to please. He sarcastically wishes her well in finding someone who can buy her everything she wants, but he makes a powerful point: real love can't be bought and sold like stocks on the "bolsa de valores" (stock market). It's a classic tale of realizing that love should be about genuine feelings, not fancy things.