Need help with my 30 Days!

Hi there! well, i can't play FF XIV ARR

It sounds like you are sharing the game / account with your friend.
You can't do that. The game is tied to 1 square enix account, which it sounds like belongs to your friend.
You would need to also purchase a copy of the game and register it to your account.

oh, i see... thanks!!

I don't know how you were sharing one game purchase between two accounts, but this is usually frowned upon and results in a ban if they know about it. You'll have to have two accounts for two people to play.