A member of my family shared his game library with me with the steam family shraing. He has the Stranger Things DLC for the game Dead By Daylight, so i now can play the characters on that dlc. I upgraded them, spent bloodpoints (the money of the game), I unlocked the perks for all of them etc... Unfortunately that DLC isn t available anymore. Does that mean that if he stop the steam family sharing with me, i will just lose everything ??? Thanks for helping me, I'm kinda scared about that !
You can't share individual DLCs, only the Full Game with DLCs. If you own the game, in this case Dead by Daylight, you will not be able to access any of the DLCs.
From the Family Sharing FAQ:
A borrower will have access to the lender's games and DLC, but only if the borrower does not also own the base game. If they already own the game, they'll need to purchase the DLC themselves in order to play it. For free to play games, DLC cannot be shared since all Steam users "own" the game.
You don't own the game right now, and if they disable Family Sharing, you will loose access to both the game and the DLCs.