Yes, you will. We still make the Joomla 1.5 version accessible to users, but no longer are planning any updates for it. It's held up very well over the year and a half since it's last version, v4.3.4. However, please be aware that Facebook just introduced a new API (programming interface). All older Facebook Applications (ones created before May 1st, 2014) can still use the older API through May 2015. That older API is what JFBConnect v4.3.4 relies on for authentication. Around May 2015 though, authentication will likely no longer work even for older Apps as they will all be required to use the new API, which only our more recent releases of JFBConnect support.
For more information, please skim through our Facebook Graph API v2 blog post. At the bottom, in the "Ugly" section, we describe the Joomla 1.5 support for the changes.
Most other features (sharing, open graph tags) are expected to continue working after May of next year, but we can't be certain of that.
I hope that helps answer your question. If you need anything else, just let me know.
Sorry about that. The Joomla 1.5 release was unpublished temporarily. It should be available again the "My Downloads" area if your client logs in and navigates there.
I hope that helps, but if you still have issues downloading it, just let me know.