This policy setting allows you to turn off OneNote's automatic pruning. With a 2013 format notebook, OneNote will automatically store previous versions of the pages in the notebook, and it will also store a recycle bin for all of the deleted pages and sections.
If you enable this policy setting, OneNote will not prune previous versions.
If you disable or do not configure this policy setting, OneNote will prune previous versions. The default value is to prune versions over time. You should only enable this policy setting if OneNote should not prune previous versions.