How to transfer songs from another apple ID into your iTunes?

I want to have the songs that I downloaded on my iPhone from my other apple ID account I want it in my other account on my computer how do I transfer them? I have them in my music but not in my iTunes on my computer

The 3rd Party transfer will solve your problem, but once you sync your apple ID, the songs will erase from the iTunes library. So you need back up the songs before you sync. I know there's a good transfer called Leawo iTransfer, that will help you to back up the data and transfer the data at will. It is really cool.