CRM stands for Customer Relationship Management. But what it should really mean is Customer Relationship Monetisation.
Most companies spend a lot of effort working through the strategies for new customer acquisition. But little is done for leveraging the existing customers – beyond the first product the customer signs up for. What is needed is to upsell and cross-sell. In effect, the metric that needs to be tracked should be the number of products that a customer is using. In most companies, the number will probably be between 1 and 1.5. Getting it to 2 or higher and thus increasing sales numbers is probably going to be easier than getting new customers.
Another benefit is that the more products a single customer users, the greater will be the loyalty. Or, put another way, single product customers are more vulnerable to switching to competition.