Battlefield 1 – Turning Tides and Battlefield 4 – Second Assault are free for the next week for both PC and console (Xbox/PSN) players. That means that if you “buy” these two expansion packs for free during giveaway period, they will be yours to keep forever at absolutely no charge at all.
Battlefield 1 or Battlefield 4 base game (sold separately) are required to play Turning Tides / Second Assault correspondingly. But you can still get these two DLCs for free even if you don’t own the base games – but you won’t be able to use them or see them in your library until you get Battlefield 1/Battlefield 4.
Those who play on PC need only to log into their Origin account, and go to the official Origin Game page: BF1 Turning Tides | BF4 Second Assault, and add Turning Tides / Second Assault to your Origin game library, and its yours to keep even after the promo is over!
It’s the same with Xbox One and PS4 users: just log into the corresponding Xbox or PS4 account, visit the store pages below, and add BF1 Turning Tides / BF4 Second Assault to your game library. They are then tied to the account forever.