NOTE: Plugin is also available on github as open source & 100% free of charge.
GL is an upgrade to the Unreal Engine games workflow, Inspired by some of the great in-house engines & technologies used by some AAA companies like pretty much every Sony first party studio for example. GL allows developers to modify a packaged game while it is running and being played on a running platform, so no time wasted in making new game packages. If you made a change, you can see it's impact on the game on the target platform right away. Regardless the game package is running on Windows, or Consoles such as Xbox & PlayStation, and regardless the game build is a shipping, debug, development or any other configuration, you should be able to update the game in no time.
In short, using GL means faster iterations than ever been possible, and at the same time a huge reduction in the time, effort & most importantly the "Cost" of game development.
Note: The efficiency of GL depends on multiple factors, such as the count & size of the modified assets per patch, the complexity of the project, the network speed (if the running game on at the same PC).