If you have one customer and one competitor you need CRM.

Customer relationship management (CRM) is a business strategy to select and manage the most valuable customer relationships. CRM requires a customer-centric business philosophy and culture to support effective marketing, sales, and service processes. CRM applications can enable effective customer relationship management, provided that an enterprise has the right leadership, strategy, and culture.

These applications support the core business processes involved with the customer
relationship lifecycle, i.e., Marketing, Sales and Service.