Reading through it again, I noticed something I had missed the first time.

"Unlock access to exclusive Premier Only content*
*Content is active as long as Subscription is active"

So content that you will have in your account but will lose access to if your subscription lapses. Presumably, that means it's content that can't be downloaded and backed-up and/or won't run in future versions of DS (free or Premier) without an active subscription. Which also probably means that you won't be able to use the Premier version of DS and any Premier content on a machine that doesn't have an internet connection, because it won't be able to dial home to verify that subscription. I do all of my work on a machine that is cut-off from the internet, so that's a total deal-breaker for me. And it sounds awfully like some of the arguments that were raised in objection to DAZ's attempt at content encryption several years ago.