Bonjour
Si vous avez coché la case de ne pa enregister vos conversations , normalment il n'y aura pa d'enregistrement. mais vous pouvez toujours vérifier allez dans ( mes documents ) et la normalment il y'aura un dossier nomé ( mes conversation historique ) . voila a+

Facebook Chat History Manager
Please update to v1.0.6. Older versions don't work now.
Chat history manager is a Mozilla Firefox extension which can save your Facebook chat messages in your local environment.
You can view your chat history anytime either online or offline.
Your messages are securely stored and only person passed the security check can view saved messages.Note that all messages are stored in your client, this application won't store your chat history on server.
Installation and usages are pretty simple.
Installation:
There are two ways install chat history manager:
1.Click below Download Extension link in Firefox, the add-on manager would prompt up.
Note that Firefox may prevent the normal download and ask for your approval.
2.Download the install package and open with Firefox add-on manager.
Download Extension New v1.0.6(43k)23031 downloads
Usage:
1.Create your account.
From Firefox menubar, select Tools,find Facebook Chat History Managermenu, and select Create Account. 2.Change your account.
From Firefox menubar, select Tools,find Facebook Chat History Managermenu, and select Change Account. 3.View chat history.
Online: view this page and click View Chat History58011 times
Offline: a.Press Controll+Alt+F to open chat history window. This need you login.
b.From Firefox menubar, select Tools,find Facebook Chat History Managermenu, and select View History.
4.Set Preference.
Set messages per page: From Firefox Tools menu,select Add-ons,find Facebook Chat History Manager and select Options.