I recently met Dale Harrison and he told me one key to loyalty is getting the customer past the third successful interaction with the company. At that point, loyal behavior can be the norm. That's one of the most valuable insights I've encountered in a long while, and is reinforced by the terrific research from Communispace, quoted below.
Although most of us won't admit being emotional about our business relationships, we all desire that they be stable, reliable and safe. That means we've been smart shoppers, and having stable relationships frees us up for more interesting adventures.
These three emotions — feeling relaxed, appreciated, and good about oneself (smart) — appear and correlate with purchase decision in many other business categories or industries. In the credit card business, for example, these emotions were the dominant difference between customers who used the card frequently or sporadically. In auto insurance, the presence of these emotions was the key difference between a brand’s customers and non-customers. While the relative importance of these three emotions varied across industries, they were consistently the major difference between loyal customers and less loyal, or non-customers.