De Wikipedia:
In economics, vendor lock-in, also known as proprietary lock-in, or more simply, lock-in, is a situation in which a customer is dependent on a vendor for products and services and cannot move to another vendor without substantial switching costs, real and/or perceived. By the creation of these costs to the customer, lock-in favors the company (vendor) at the expense of the consumer. Lock in costs create a barrier to entry in a market that if great enough to result in an effective monopoly, may result in antitrust actions from the relevant authorities (the FTC in the US).