A session can be saved and restored later. A "session" involves the files loaded, bookmarks, annotations, layer settings, hierarchy settings, images and application setup. Sessions are stored as XML files with the suffix ".lys".
To save a session, choose "Save Session" from the "File" menu. To restore a session, choose "Restore Session". KLayout can be started with a certain session using the "-u" option from the command line followed by the session file. On Windows installations, session files are registered as being opened automatically by KLayout.