Apple’s Passbook app and system lets you use passes that contain time-sensitive or location-sensitive information. For example, you might have a pass that triggers when you enter a specific store, like Target. Or, you might have airplane tickets going through Passbook, if you use that specific airline’s iOS app.
The ideal here is that the passes show up on your lock screen, so you don’t have to launch an app. This doesn’t always work, however. What can you do when it doesn’t? I’m glad you asked.
First of all, if your pass does not appear in your lock screen, unlock your iPhone with a swipe and launch Passbook. Select the pass in the Passbook app and scan it from there.
There are a few reasons your pass might not show up in the lock screen. One, Location Services may be disabled. Open up your Settings app and scroll down to Privacy. Tap there and make sure that Location Services are on generally, at the top, and scroll down to the Passbook icon to ensure that Location Services are on for Passbook specifically.
Each pass also has a specific toggle switch to be seen on the Lock Screen. Open Passbook and select the pass that’s not showing for you. Then, hit the little “i” Information button in the lower-right corner of the pass itself, and then toggle Show On Lock Screen to ON.
Not every pass will show you this option, as not all merchants or pass makers support the Lock Screen feature. If that’s the case, you’re sadly out of luck.
Source: Apple Support