Barring the bug fixed in v.76, you are eventually blocked from gifting a license to someone who already has one. I’ve moved the check earlier on to improve the user experience. Changed in v.77 
Idea
However, there is always an unavoidable race condition where you gift a license at exactly the same time they are purchasing one for themselves.
Strangely, that’s the way I originally had it originally. Reverted Idea
I completely forgot about that. I’ll add it to v.77 Idea
It’s currently the same. I need to conserve resources on the server, so inactive players need to be cleared out periodically, regardless of their platform (desktop, Steam, mobile, etc)
It’s to avoid fraud (creating dummy accounts and then gifting items purchased with stolen credit cards). But I agree it offers marginal protection. The real question is, what proportion of players would gift before making a purchase for themselves? Is that a common thing? I don’t know. Has anyone here ever done it?
Can’t, because of the way the enemies are laid out. Besides, how feasible would some left-to-right,top-to-bottom order be?
I only did that to investigate a potential bug.
I get… uh… 2.98%. But I see there’s something going wrong in my formula. I’ll need to rework it.