Hard to predict as this will vary with export resolution and quality.
With large source files and a lengthy project you may want to consider editing it in several small parts, to ensure that it will export without freezes and missing content which can result if the program runs out of memory.
Completed work, after export, is just a file. The original edits won't be available. But then those files can be reimported into VP for final export.
Regularly back up your work with Save Project AS, giving it a unique name or #, so as to not overwrite earlier saves. If Save Project (no AS) is used, it will overwrite.
Then you will be protected.