Depending on your plan, 1, 2 or 12 credits will get added to your account on your renewal date displayed on your plan page. Credits can be used for physical books or audiobooks.
You will have a free credit added to your account if someone you referred joined. You can see the number of free credits you received from referring friends who joined here. These credits cannot be used for your monthly selection, but can be used for add-ons or audiobooks. You also get a free credit when you purchase 5 audiobooks. Read more about this in the audiobooks section below.
Sometimes you might have a coupon added to your account to be used on a free add-on if: you are a BFF and it is your birthday month, you purchased a 6 or 12-month gift during holiday promotional periods, or other.