Customer loyalty and the impact of promotional strategies are key factors in driving sales and maximizing consumer satisfaction in the retail industry. This study focuses on analyzing customer purchasing habits on the In-stacart platform, with two main objectives: identifying the most re-purchased products and measuring the influence of promotions on purchasing behavior. Using a large dataset of purchases, we applied segmentation techniques such as clustering to group customers based on their buying habits and analyze their reactions to promotions. The results show that certain products, such as bananas and organic strawberries, benefit from particularly strong loyalty, regardless of the presence of promotions. However, promotions play a significant role in increasing order volumes, though they do not necessarily attract new customers. This study highlights the importance of consumer goods in fostering customer loyalty and proposes avenues to optimize promotional strategies in the retail sector.