Free iOS basic license for Unity 3.x?

I just downloaded Unity 3.5.7 in order to build an iOS game (my Mac is old and stuck with Xcode 4.2, so Unity 4.x games crash on startup). I’m familiar with building for iOS with Unity 4.x, but Unity 3.5.7 tells me “your license does not cover iOS publishing” and sends me to the store.

In my Unity account online, I see a Unity 3.x add-on “iOS 3.x” serial key under the Licenses section, but I cannot find where I should use that in Unity. I know that basic iOS publishing in Unity is free now, but I’m not sure how to go about that in Unity 3.x.

(Also, I’ve already tried the trick where you extract the new iOS SDK to use with Xcode, but the app still crashes at startup even when I am able to target iOS 6.)

This isn’t really a Unity problem, it’s more of a buy-a-new-computer problem.

By ‘new’ of course I don’t mean go into an Apple Store and plop down $3000, I mean go on Craigslist and get something like the 5-year-old MacBook Pro I am currently using to run the latest Unity and XCode with no problems.