How to continue the render later?
You may either activate the switch “write/resume FLM” in the exporter and have automatic save/resume, or manually “Save/Resume FLM” under “File” in the LuxRender app. Save when you’re about to close the app and “Resume” when you want to later start the render from the point last saved. “Load FLM” doesn’t restart the rendering automatically, you should hit the “Resume rendering” button manually.