Each day companies are losing their customers. There are a lot of reasons why customers leave, but recent surveys show that almost 70% of customers leave their service supplier companies because they felt undervalued. Most companies build their marketing and business strategy focusing on bringing in new customers. They spend a lot of energy, money, time and forces to get reach this goal, but almost always existing customers are forgotten. In a modern world companies are oriented on gaining a profit, but not to reach a warm and reliable relationships with customers.
Very often existing customers seems to be uninteresting to service supplier company anymore, as they have already paid for the service. This strategy leads to company's bankruptcy. Indeed, it is more valuable to have a life-time user, who pays less but constantly for your service then gain a new customer who will leave you because of lack of attention from the side of customer support department. Furthermore, this user will tell others about your strategy in blogs, forums, etc. You should make everything for customer to stick to your company like a glue. Trust me - you will win in a future.
There is a back side of a medal, when long-term customers are trying to reach more than they have paid for motivating of being already 4 years with your company. Surely you may have some discount promo-actions for those who are already e.g. 3 years with your company, you may provide your service free during 1 month for them, etc. But do not let customers to feel like they can manipulate you only because they have spent a lot of time being with your company. It is better to clarify from the first days of a deal what customer may get and which advantages he/she may achieve in a few years. It will save your time in future and protect you from long and unnecessary correspondence.
The other nice way to keep your customers is to make your web-site interesting for them. Make different videos of how your product works, how to operate it, etc.. Video manual will help your customers greatly. Furthermore - when your site looks attractive even a passerby will stay at your site to learn more about the service you provide. Surely your site should not look like a Christmas tree, but it should not scream SELL SELL SELL as well.
Customer loyalty program is an expensive, time consuming but extremely necessary thing to protect your business. Think about it.