Transferring iTunes Match from one Apple account to another

My husband was told years ago to set up Apple Match for his own music that he downloads to an iPod via his laptop. He did this using my apple account. He has just recently bought an iPhone (so now has his own apple account) which he directly downloads the music to also. He does not stream music from any other source. Is he wasting his money having iTunes Match? Don’t want to cancel the standing order if it’s going to mess things up and delete all the music he has downloaded already. Also need to know if it’s possible to transfer the iTunes account to his apple account. Went into an Apple Store and the guy had never heard of the product. Not very reassuring. Does anyone have any advice? Thanks.

[Re-Titled by Moderator]