I'm asking cause this is the #1 thing I worry about a lot. I notice they don't but I might be wrong so I want to ask first.

I currently do have a code for 5 free songs for Rock Band 3 that I do wish to use. (This is why I'm asking btw)...

So ye'h... Can codes ever expire or not?

Depends on where you are usually. Like gift cards can't expire or be charged inactivity fees in the state of california.

Generally if they don't have an expiration date, then they do no expire.