OP: Did you register your game before May 31st of this year?

If no, you couldn't have gotten legacy anyway. If yes, just keep paying normally and you'll probably get it.

And if you don't qualify at all, so what? The entry-subscription is one dollar cheaper than legacy anyway, and still gives you one character per server up to a maximum of 8 characters. If I weren't going to get legacy, I would have gotten that sub and not care more about it.