Originally Posted by COOPFAQ
Q. How is my progression saved when I am invited to join a friend’s game in co-op?
A. The player invited in the host’s game is essentially a “Friend for Hire”. When you join a co-op game as a guest, you are playing in your host’s world and help them progress.
This means that once you leave the co-op mode after a game as a Friend for Hire, you do not keep the World Progression completed during the co-op session. However, you keep your own Player Progression – XP, in-game currency, inventory items, and more – once you leave the co-op game and are back in your own world.
Q. What progression is not saved when I am playing co-op as a guest?
A. As the guest, your World Progression, Reputation, and Quest related unlocks are not saved once you are back to your own world.
Q. What is the Player Progression?
A. The Player Progression is your personal progression including your XP, your in-game currency, your inventory items, your items purchased in the shop, your challenges completed, etc. Some specific items unlocked during quests in co-op will not be saved after leaving the co-op session.
Both host player and Friend for Hire keep their Player Progression in co-op.