If you have any other open companies on hosted Enterprise your online backups on Intuit servers will continue to be accessible https://enterprisesuite.intuit.com/in-product/quickbooks/online-backup/activate.jsp

If you are shutting down Enterprise altogether I suggest contacting @Anonymous and pay him to create a local backup for you as I do not think you can save the Intuit hosted backup locally or even create your own local backup in Enterprise.

However if you can, (from menu bar File>Create Backup or similar) just create backups saved locally and store in a secure location.