When you set content.ini [VersionManagement] DefaultVersionHistoryLimit on a site where it wasn't set before, or reduce an existing setting, eZ Publish does not delete existing old versions whose count is above this limit. (They are deleted one by one on editing, which only helps when you edit and cancel, and they can be deleted manually in the versions management view.) This should be handled in a cronjob (perhaps it makes sense to add it to an existing cronjob).