It works well but only for the immediately previous session. Sadly, it does not save from multiple previous sessions and so, is not as functional as I'd hoped.

Useful for saving multiple tabs. The extension saves all the currently open tabs, which can be restored in the next session.

SO FAR SO GOOD! I just started using Save Tabs, so all I've done is save my tabs, close Firefox, then reopened it, and it restored my tabs. And it worked just as it said it would! That is a high complement, as most add-ons descriptions make the add-on sound easy and simple to use, but then you install it and it takes hours to figure out. I'm sure there's more this add-on does, and I will attempt to learn more, but to have it do the main function as easily as flipping a light switch is so very nice and such a relief!

I thought you could save tabs to a file but that's not what this addon does. I found https://addons.mozilla.org/en-US/firefox/addon/export-tabs-urls-and-titles/ that can save (but not restore) tabs.

Installiert und einmal angeklickt.
Ergebnis:
"NoScript detected a potential Cross-Site Scripting attack
from https://mybrowseraddon.com to https://www.facebook.com.
Suspicious data:
URIError: malformed URI sequence,(URL) https://www.facebook.com/plugins/comments.php?api_key=&channel_url=https://staticxx.facebook.com/connect/xd_arbiter/r/lY4eZXm_YWu.js?version=42#cb=f24df40be12172e&domain=mybrowseraddon.com&origin=https%3A%2F%2Fmybrowseraddon.com%2Ff391dfe8729722c&relation=parent.parent&colorscheme=light&href=http://mybrowseraddon.com/save-tabs.html&locale=en_US&numposts=10&sdk=joey&skin=light&version=v2.0&width=100%"
Ungefragter Versuch Daten abzugreifen führt zu schlechter Bewertung und deinstallation

I didn`t get why i should save ALL tabs instead of just one

Handy for restoring tabs that are accidentally closed and when restarting the browser. Pretty limited functionality tho overall.