To take advantage of the promotion, open the Apple Store app, scroll down, and tap on the Day One 2 banner. Read the terms and conditions, tap on the green "download now for free" banner, sign in to your Apple ID account, and tap on "Redeem" in the top-right corner. The app will then begin downloading automatically.
Day One 2, normally $4.99 on the App Store, allows you to create a journal your life, ranging from once-in-a-lifetime events to everyday moments. The app features a timeline for browsing through past photos and notes, while you can also record the location, weather, time, and date of your life experiences.
Day One 2 is available on the App Store [Direct Link] for iPhone, iPad, and iPod touch.