Final answer:
The computer program that is free initially but requires a payment for continued use after a trial period is called shareware.
Step-by-step explanation:
The type of computer program that is available for free on a trial basis and then requires a fee for continued usage is known as shareware. Unlike freeware, which is completely free to use, or open-source software, which provides access to the source code, shareware offers a trial period during which users can evaluate the program before deciding to purchase it. This contrasts with proprietary software where the source code is not shared and the software must be purchased or licensed for use.