Because a F2P download client won't have:
Original Star Trek Uniform Set: Three uniforms from the original series (blue, red, yellow).
Exclusive “KHAAAN!” Emote: An unforgettable moment from the second Star Trek Film. This exclusive emote allows players to relive Kirk’s unforgettable moment of fury, with the timeless cry… “KHAAAN!”
Exclusive Klingon Blood Wine Toast Emote: Raise a glass like a Klingon! Greet other players with an exclusive Klingon gesture –the blood wine toast.
Unique Registry Prefix: Give your ship the coveted NX prefix, seen only on a handful of elite Starfleet vessels like the Defiant, 22nd century Enterprise, and Prometheus.
Unique Ship Item: Automated Defense Battery. This Tactical Module grants any ship a passive 360 arc attack power with a short range.
The game also includes a Steam-exclusive Phaser Turret – This Tactical Station Mod allows you to deploy a small space phaser turret. After redeeming your key, your exclusive item will be available in the C-Store’s Special Unlocks tab.