http://www.roboform.com/for-firefox-windows
That site says the latest version is 7.5.1. Is that the version you
have installed in Firefox?
I did a search at
addons.mozilla.org on "roboform" but got no hits.
Seems odd Mozilla would remove or never list Roboform at their official
extensions site. The download link at Roboform's site points to their
own .exe file from their site, not back to Mozilla's extension site.
Odd they won't publish their extension at Mozilla's site.
Maybe that is because Roboform is commercialware ($20/year; see
https://www.roboform.com/php/pums/rfprepay.php?lic=default_alt&lang=en).
Did you not renew your subscription to Roboform? There is upgrade info
at
http://www.roboform.com/faq#faq_upgrading. It looks like you have to
pay for version 7 unless you qualify for an upgrade but that lasts only
for a 1 year subscription, and it's likely that the latest version of 7
is required for compatibility with the latest Firefox.
They mention there is still a free version available but now I remember
why I panned this extension when I looked at it previously. The free
version only allow 10, or less, logins that it will store. That's
hardly worth using this extension. It's enough to play with to see if
it is something you would like to use but not enough to really matter to
most users since most users would be visiting more than 10 sites where
they have to login. But why would Roboform still not list their highly
crippled freeware version at Mozilla's extensions site?
Is their extension not signed? If so, it will get disabled if already
installed when you upgrade Firefox, or you won't be able to do a new
install of it. Firefox v48+ requires extensions be signed; see
https://wiki.mozilla.org/Add-ons/Extension_Signing.