What is the premium currency and how do i get it?

Premium currency is the most valuable currency in the game. At the moment, you can get free premuim currency in several ways: by clicking on dwellers' emotions and taking out garbage outside of a the house (there is a chance of getting a certain number of premuim currency), by completing achievements, by opening chests or by completing certain missions. However, one of the easiest way to get premuim currency is to buy them in the Store.