Subscriptions are now available to purchase for EVE Online on Steam!

Users that purchase the new EVE Online - Gallente Bounty Hunter Starter Pack are eligible to purchase a Subscription & PLEX. PLEX is an in-game item that can be used to pay for your subscription without using more traditional payment methods.

Steam customers may now sign-up for, manage, cancel or renew game Subscription Plans at any time, online directly through Steam.

Source at Steam