Becherovka is a herbal bitters, often drunk as a digestive aid, that is produced in Karlovy Vary by the Jan Becher company. Becherovka is often described as having a gingery or cinnamony flavor. It is made from a secret recipe based on a wide variety of herbs and spices. It is usually served chilled, though some serve it with tonic water, making a drink called a beton (becherovka and tonic) which means "concrete" in Czech.The Jan Becher Museum in Karlovy Vary is devoted to Becherovka. Your task is to visit the museum and take a selfie in the souvenir shop with bottles of Becherovka.
Information about opening hours and entrance fee can be found here, but only in czech. Here is a little summary for you:
Opening hours: daily from 9AM to 5PM
Entrance: Adults 120CZK, Students (ISIC card) 60CZK, Children 30CZK, Family (2+2) 240CZK
Commentary available in English, German and Russian.