Question: "Optimize Storage" requires subscription?
I have a big music library, and my iPhone enjoys syncing as much as it possibly fit on my device, then complains constantly about not having any free space. It looks like the "Optimize Storage" functionality would take care of this no problem, but I'm not allowed to use it unless I subscribe to some silly cloud service I have no interest in. I'm not paying $10 a month for a convenience feature that's already on my phone.
Thanks in advance for instructing me how to activate Optimize Storage without having to pay a subscription fee for it.
iPhone 5s, iOS 11.1