It's a lifetime license, but it will only apply to Construct 2 - when we release Construct 3 that will be a different product, but we're not even planning it yet, we have a lot of work to do on Construct 2 first.
We can't confirm any plans about an EXE exporter at this stage I'm afraid, we still have a lot to do on the HTML5 exporter.
The same goes for Android, but you can already get games running on Android via the browser, or by PhoneGap (currently experimental, and hopefully should work better when Android 4 comes out).