How long is a lifetime?
No one lives for ever. That is especially true of customers. They come and go with increasing frequency, and 'loyalty' is a tenuous concept at best. No wonder that CRM (1) is the flavour of the marketing decade. In its broadest sense, it is the best defence we have against customer promiscuity.
Every good merchant knows that his best prospect is the person who bought from him yesterday: if he can provide a product and service that satisfies that customer, there is a strong likelihood that he will return to purchase again and again and again. That is why we are often offered 'loss-leaders', products priced so competitively that they are almost irresistible and become the entry point of what is hoped to be a long and profitable commercial relationship.
But we also know that everything we do must hold its own against a noisy background of often fierce competitive activity. If a customer is good for us they will almost certainly be worth seducing away: the more business they do with us the more they will be courted by our competitors.