As iOS 8 is out, there is a feature that show \"Suggested App\" on lockscreen based on your location.
The question is if I have an app, how can I define the location
So far there is nothing in the App Store submission process to allow you to define locations where your app should be 'promoted' on the lock screen. Using Beacons is the only available option.
It would also appear, based on my own in situ testing, that the Apple App Store App is also doing some 'suggestions' based on apps that are frequently used in your current vicinity. In one example, I was in a grocery store, and the App Store icon appeared. When I slid to open, it took me directly to the Grocery store chain's app. That app wasn't on my phone so there was no beacon interaction. This looks to be using the same "popular nearby" crowdsourced data.