Because your friend is Adding songs to his library by clicking on the plus sign while you are clicking on buy in iTunes which will still cost you the price of the purchase. If your friend drops Apple Music his 300 songs will disappear, the ones you have purchased will not.
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Because your friend is Adding songs to his library by clicking on the plus sign while you are clicking on buy in iTunes which will still cost you the price of the purchase. If your friend drops Apple Music his 300 songs will disappear, the ones you have purchased will not.
iTunes - Official Apple Support
Try contacting iTunes support and ask them.
This is a user-to-user technical help community. We do not have access to your iTunes account.
Why am I getting charged for downloading music on iTunes when I just joined the monthly deal of unlimited music?