Language Tool for Firefox ESR 45

Hi, I need a piece of informatin and a help, please.
The add-on LanguageTool Grammar Checker is the official successor of LanguageToolFx (only for old versions of Firefox). LanguageTool Grammar Checker requires Firefox 48.0 or later. LanguageToolFx has been removed from https://addons.mozilla.org and I can no longer use it on Firefox 45.4.0 ESR even if it is a version that is still supported by Mozilla and whose end of life is 13.6.2017 (the date when Firefox ESR 52.2 is scheduled).
How can I go on using the add-on without having to upgrade Firefox to version 49.0.2?
Thanks in advance and greetings everybody.

This is a Overview of Firefox ESR and this is Mozilla Firefox Release Schedule, in case someone need more info.

You can’t, sorry (unless you modify the code). We had changed our internal APIs and LanguageToolFx would have needed an update. Considering the very low usage of Firefox ESR (less than 2% of the LTFx users were on ESR), I decided it’s not worth the effort.

Thank you very much for the answer.
I understand you prefer to invest your time, your work and your resources on the new addon instead of the previous one. I comprehend that making the new addon compatible with Firefox 45 would request an effort, but it would be appreciated.
I chose to use the Estended Support Release since there are reasons why I cannot use version 49.0.2 or a beta o a nightly. When I say that “I cannot” I exactly mean that I cannot, I do not have the possibility to use a different release.
I guess that there’s no possibility to get a copy of LanguageToolFx because it no longer works due to the change of your internal APIs.

I understand that this is a small percentage, but, respectfully speaking, the result is that I, as a part of a minority, do not deserve any effort or consideration. I as a person and happy user of LibreOffice LanguageTool and LanguageToolFx am not worth the effort…
Please forgive me for my not being completely satisfied…