Neptune ships with Persistent Creator an easy to use application to create a persistent file for your live usb stick to save changes from your live system.
Your Live USB Stick needs to be created by Unetbootin or another application which uses the Fat32 partition format. This is necessary for persistent creator to create its persistency file (live-rw) which will contain all the changes done to the live system.
You have to keep in mind that Fat32 has a file size limit of 4 GiB. So you cannot create files bigger than that. We recommend a file size of 2 GiB. Minimum is 1.5 GiB
After the creation of the persistency file the boot area will be changed automatically so that this file is taken into account on the next live boot.
As this file is just a normal image file in which uses the ext filesystem you are able to mount it on every linux system with the mount command. This allows you to create backups if necessary. A filesystem check (fsck) on this file is also possible.