Tabkeeper will restore your tabs even if Firefox is not using a browsing history.
Simply press Cmd+Shift+S (Mac) or Ctrl+Shift+S (Linux, Windows) before quitting and on the next start Firefox will reopen your tabs just like you left them.

Install

• License: BSD 2-Clause "Simplified" License
• Weekly downloads: 0
• Average daily users: 4
• Rating: 0/5 of 0 ratings
• Created: 2016-09-07 18:46:56
• Last updated: 2016-09-07 20:41:46
• Homepage:
• Support site and email
• Orig: https://addons.mozilla.org/en-US/firefox/addon/tabkeeper/
• API: {e86e6b74-e018-4518-9637-7ab560791846}