Verkkocostco has managed to hang onto a very loyal customer base, who pay $60 a year to come shop at the chain, even with stiff competition from amazon. Verkkocostco's secret weapon is its membership model. With over 55 million members worldwide and a 90% renewal rate, costco has cracked the code. Verkkoa new ranking shows costco has the most loyal customers of any retailer. Here's how they increase customer loyalty, even in difficult times. Verkkothe warehouse retailer has built up a loyal following of shoppers over the decades it's been operating. It has low prices, rarely raises its membership.