Hi texla
Yes, as mentioned by bitsnpcs, persistence is one way to go. But you can also do a full install and run most Linux distros from a usb stick/drive providing the size of the usb stick is big enough in terms of gigabytes. This will give you the 'persistence' that you get from a normal install.
For the record, I've installed Linux Lite, Xubuntu, Lubuntu, Sparky Linux, LXLE, and Deepin permanently on a 16G usb stick (only one at a time, of course!) . The following tutorial explains the basics -
http://ubuntuhandbook.org/index.php/2014...usb-drive/
(In above link, ignore the 'Windows' bit unless it's relevant to you -
you only need to create an EXT4 root partition and a small swap partition in step 6.)
Just be careful to identify the designation of your usb stick via Gparted (dev/sdx - 'x' being whatever the designation of the usb drive is) and make a note of it for the creation of your root partition and also, equally importantly, for the placement of your boot loader which should be the same designation as your
usb root partition.
Have fun!