Music Purchased on iPhone through iTunes BEFORE subscription was even an option.

Over half of the music I have purchased through iTunes over the last 15 years I don't have access to. When I go to play the songs, it tells me I need to subscribe to Apple music. I have NEVER had a subscription, all my songs were purchased through iTunes and never during any subscription of apple music. So I'm being robbed of things I paid for. Why can I not listen to the music I paid for? This is unacceptable.