GSview 5.0 is technically "nagware" rather than strictly locked software; it does not require a registration key to function
Originally, GSview was distributed by Ghostgum Software Ltd. as "Aladdin Free Public License" software for a period, and then as "Ghostgum Software Shareware." Users were encouraged to pay a small fee (around $40 AUD at the time) to receive a registration key that would: Remove the annoying start-up nag screen. gsview 50 registration key
Artifex GSView 6.0 (Beta): A newer attempt at reviving the tool, though it differs significantly from the classic 5.0 interface. A Note on Safety GSview 5
Purchase from Official Sources: The most straightforward way to obtain a registration key is by purchasing it from the official GSview or Glyphs, Inc. website. This ensures you're getting a legitimate key and supports the development of future versions. A Note on Safety Purchase from Official Sources