Starting with version 2.73, Loyverse POS for iOS, working on iPhones, and 2.40 for Android Smartphones, has a new functionality called Favorites. 

Favorites allow cashiers to have quick access to the most used items to add them to the ticket during selling.

To access the feature, select  ‘Favorites’ from the ‘All items’ drop-down menu. 

For more details about Favorites, see the help article: How to Use Favorites on the Sale Screen of Smartphones.