Secret World Legends is free-to-play, but you’ll want to subscribe. You’ll be able to play and win the game without spending a dime, mind you – but having a monthly membership gives enough benefits to be worth it, assuming of course that you like conspiracy-horror shared game with fiendishly complicated investigation missions and a cheerful willingness to throw everything into the mix. And I do mean everything.
Here is the SWL fact sheet for navigating the Steam launch. You may want to take a look at it. The process might be a little… complicated.