Hey i want to play with my friend, How does it work? i have paid for it but does the person need to pay for it too or not?

Looking for someone to play Shared Story

I`ve bought the game about year ago, now i wanted to activate in another account a key which it gives to me, and i accidentally active it ON THE SAME ACCOUNT. ON WHICH I HAVE GAME, and now i cant use this key on another account because it is already activated on account with this originally purchased game, what the ****??????...

Если еще люди остались, которые хотят пройти кооператив - напишите. Во первых хочу открыть ачивку коопа. Во вторых понял, что самую правильную концовку можно открыть только в кооперативе и если собрать все данные вместе и логически рассуждать персонажами. Сам в кооп ни разу не и�...

As the title states, I'm searching for a partner to get the 'Shared story' achievement on Steam. Anyone up for it? Add me on Steam friends