I seem to be finding confusing information,

is battlefield 4 premium an annual subscription? or a one time buy?

One time buy. It's just a bundle for all the BF 4 map packs basically (plus some bonuses I'm sure).

It's just a fancy way of saying it's a season pass for all the DLC with weekly benefits (battlepacks)

When battlefield games become annual releases, then it will be.

No; its better to think of it as a one time purchase for each title.

Thanks guys, yeah that's what I thought, but the guy at the store was warning me that it only lasted a year and that EA games has delayed the releases of the packs because "the game was shitty". I thought it was pretty big BS but was just curious.