I have written a song that starts out in the key of F. No problem there, but I smoothly (I think) move into the key of Eb for the middle part. However, I have discovered that when I get to play the final few bars to end the song, I am still in the key of Eb. I have tried to modulate back to F, but the chords to get back don't match the melody line and just don't sound right to me unless they are in Eb (you all may remember I am an "ear player," so music theory books don't help me at all!). Anyway, my question is: is it musically acceptable to start a song in one key and end it in another, or should (must) it return to the original key to conclude? I hope this isn't a dumb question, but then I have been known to ask dumber ones in the past! Thanks for any sort of response or clarification for me. If you need further clarification, just let me know!

Ted