An individual service is not the same as a one-time service. Compare the recruitment of a new employee (an HR individual service) to the maintenance of a company's ledger and books (an Accounting individual service). In this example, the HR process is a one-time service that ends when the new employee has been hired. The Accounting service, on the other hand, is far from a one-time service, and is instead an ongoing process, month over month, in perpetuity. Ergo, even though both are individual services, both are not one-time services, and have different pricing models.