About this Add-on
You may unable to restore multiple tabs because the user pref browser.sessionstore.max_tabs_undo is 1 by default. If you need to restore more tabs, you have to change the pref value bigger according to your preference.
To create your own collections, you must have a Mozilla Add-ons account.
Some add-ons ask for permission to perform certain functions. Since you’re in control of your Firefox, the choice to grant or deny these requests is yours.
Please note this add-on uses legacy technology, which gives it access to all browser functions and data without requesting your permission.