The first free month offer has ran for a while now but it looks like that has been nixed as of this week, according to PWInsider. The billing page for the WWE Network now includes the following message:
"WWE Network subscriptions are billed in advance and recur monthly. Billing starts on the date you subscribe or reactivate your account subscription, and re-bill on the same day each month until cancellation."
It's likely that the free month for new paid subscribers was dropped because subscribers can preview the WWE Network all they want with the new free version. The paid version is still $9.99 per month.