Unable to login or register API Key error

I'm getting the following error:
Invalid API Key:
The application you are trying to access does not exist or has been disabled.

I'd recommend creating a new test Facebook application and trying that API/Secret key. It's possible that, like stated above, your key is correct but has actually been disabled by Facebook. This can be due to violations of their terms of service. I've only heard of this happening once or twice in over a year of JFBConnect development, so it's unlikely. If it is the case though, you'd have to contact Facebook for why it was disabled.

If the new FB application works, you can always stick with that. If you had lots of users and 'stuff' with the not-working application though, this may not be a good option.

Ahh. I looked at your page again and looked through the source more closely after your last post. You have 2 calls to Facebook initializing the API and both are specifying a different API key. Per Facebook guidelines, and their API requirements, you can only use one API key per page.

Additionally (and I thought I searched for this yesterday and didn't see it), you are using some add-on which uses the newest Facebook library. JFBConnect still uses the previous version. Unfortunately, the 2 libraries are incompatible and cannot be used together on the same page. We're very close to the next major release of JFBConnect which uses the new library, which will resolve that incompatibility.

This latter point has nothing to do with the 2 API keys, as that is the main issue.

Regarding refunds, as described in our FAQ, we do not. We are selling GPL software which is 'open' software. Therefore, there's no way to nullify a purchase. You are paying for access to download the software and our top-notch support here.
www.sourcecoast.com/extensions/subscription-faq

The reason the button is not showing is because Mootools is not being loaded. Our application tries to load it, but there are scripts, templates, and 'optimization' components which try to prevent it from loading. It's absolutely required to have it for Facebook features to work.

Please try to investigate why Mootools would not be loading. If you need help narrowing it down, let us know and we'll see what we can do.

Mootools is a javascript library which is included with Joomla. There's some templates and extensions which try to prevent it from loading to speed up the page. However, that's annoying because some extensions (like ours) require it. If you can PM us a super-admin account to your site, we can try to investigate what's preventing it from loading. You can PM us by hitting the down arrow next to my name and clicking the mail icon.

The like button module will be included in the JFBConnect 3.0 package which will be available very soon (few days). It should be a painless upgrade from the 2.x line and is free for all active subscribers.