The activation is not inside Flight sim, but it's tied to the hardware, so:
- regardless if you use FS9 and FSX, or FSX only, or FS9 only, on one PC, it will always count as 1 activation
- regardless if you use FS9 and FSX, or FSX only, or FS9 only, on two PCs, it will always count as 2 activations
And second question, how do I know how many activations are left?
You don't but, it should't be a problem, since you have 6 of them, and you have 2 computers, and one is a laptop that can't change major hardware components, so it shouldn't consume additional activations like the first one.
And, there's the auto-reclaim of old activations every 90 days, which makes really unlikely you'll ever consume your available ones.
And, even if you do, there's always the chance to ask for a reactivation via email.
Really, activation is never a problem: we had to reactivate a few people only, most of the time we get email from users that thought to have finished their activations, when they used only 1 or 2, but they email nonetheless, usually becasue they lost their purchase receipt, and there's an automatic provision even for that, without having to email us.