There is a problem in the current version of Pure messenger with Facebook … it doesn’t keep the Facebook login token.
To ‘solve’ this, in the widget settings page, you need to unlog FB in widget settings, accept delete account settings, then relogin.
The next Pure messenger version will solve the issue, BUT you’ll may have to relogin one more time when the new version will be released (in 1 or 2 days).
Sorry for the convenience.
EDIT : version 2.3.1 solve the issue, but after updating, you have to unlog FB in widget settings, accept delete account settings, then relogin.