On iOS and Mac, with iCloud your projects will be automatically restored so you can uninstall the application and even reinstall it on another device without losing your projects if you are connected to the same iCloud account.

If you do not have an iCloud account enabled and on other devices (Android and PC), in order not to lose your projects you can save them with Dropbox, by email, in the folder of your choice on PC, or on a On-line storage service.