Bluebeam Revu needs an autosave option like what exists in Word where you can set it to save every so often in case it crashes or something happens to your computer. Also, I know it's supposed to prompt you to save changes when marking up a PDF, but that function doesn't seem to work consistently. If I accidentally close the whole program instead of an individual PDF there's no prompt to save your unsaved changes. I lost several hours worth of work this way.