The reason for this is that your company's ExpenseIn administrators will have disabled the out of office functionality and you are not on a current version of the ExpenseIn app.
You should always be using the latest version of the ExpenseIn mobile app, but you must ensure that your mobile app is at least version 2.5.1 to prevent you from being logged out. You can check your version number by following the How to check which version of the mobile app I am running article at the end of this article.