This is by far not the only gotcha in Facebook apping.
The Applications Settings form is a magical mess of spagetti logic. The first thing your learn is your can't even access the most useful applications settings in the form unless you choose "other users can install this application" ... then magically the form explodes with all the options you really need to set ... wtf? ...and then the About text for your app is entered in two different forms. Choosing developed by a company vs. developed by individual causes different kind of linkage on the app About page.... The most drunken delusional designer at Microsoft could not design a worse form than this.
Another thing you learn on your own is Facebook does not tell you the end user's ID unless the user installed your application. Their docs talk about the login process but are silent on explaining the difference between login vs. install which leads to this madness about "infinite sessions". All it means is if the user installs your application == infinite session. If user "logs into" your application == 24 hour session. Needless to say it is easier if user installed your application, again not mentioned in the docs.
Oh and another thing, Facebook does not save application data for you. Saving user settings and data is totally your problem to solve. It'd be nice if Facebook had an API to stash just a little bit of data for each app user but no dice.
...oh and finally try submitting your application to the product directory... SORRY! Your application needs to have at least 5 users before it will be listed!! How does an application that hasn't lanuched yet and isn't even listed get 5 users??? Such are the mysteries of Facebook.