We hope that when you used a lot of these cards it was for good and permissible purposes, because if it was used for the opposite then your using them will be compounded by other sins too, so you should pay attention to this fact.
As you have acknowledged that you were wrong to take these cards without your parents’ permission, you have to repent from doing that – praise be to Allaah Who has guided you to repent and regret your actions. But you should understand that there are conditions for repentance, which is not valid unless they are met. These conditions include: immediately giving up the forbidden action, resolving not to go back to it, and restoring people’s rightful property or seeking their forgiveness. You do not have to tell your father what you did, rather what you have to do is to return the money in whatever way you can. You should try hard to figure out the value of the cards you took without your father’s permission, and give this money to him.
We ask Allaah to accept your repentance and to guide you to do righteous deeds. And Allaah knows best.
And Allaah knows best.