Apparently a new password management function is in the works:

https://www.bleepingcomputer.com/news/software/firefox-to-get-a-better-password-manager/

I used Saved Password Editor and Password Exporter, including storing their icons on the new add-on bar (since Firefox devs also continually enjoy removing items users want and need and find useful) and Lockbox doesn't appear to be anything like those, as it appears to emulate those third party cloud apps I have no intention of ever using.

When can we expect Firefox devs to actually implement something that is necessary without the use of an add-on for which they always break functionality with every new release? And why can Noscript be updated for use in 57, but not Febe or the password apps? Or any of the myriad other useful apps that are now just listed on a legacy page as if for fond remembrance?

Here are your choices; 1) Contact its support and ask if they will update 2) Find a replacement 3) Downgrade to a prior Firefox 4) Do without

In the event that the passwords information is lost, you should record all information in a separate text file somewhere else on your hard drive, or written down. You can easily copy and paste if you need to do so. If you are concerned about someone else looking at that file, you can compress it using a password.