Instruments used in the song include a LinnDrum machine, Roland SH-101 keyboard for the bass, and a Roland RE-501 loop echo to add warm backing vocals. "The Promise" is in the key of C major.
In the context of music production, "The Promise" incorporates a LinnDrum machine, a Roland SH-101 keyboard for bass, and a Roland RE-501 loop echo to enhance its sound. The song's composition is rooted in the key of C major.