Currently, it is free to play but you have limited access like some skill trees are locked and some of the features are not available to those who are not paying monthly or haven't bought P.L.E.X. (Pilot License Extension)

This gift gives you access to 1 months of Omega Account which allows you with full features. After that if you want to continue using omega, you either have to have P.L.E.X. or subscribed to the game.