At least in the USA, it’s pretty much as far back as they allow, given that the shoes are unworn and with tags/boxes. I’ve returned stuff that was unworn that was 4 - 5 years old (and unworn). My suggestion, would be to buy the $40 deschutz, and when it arrives at your house, then mail back the $40 new deschutz to Nike. They’ll refund you the original $$$ that you paid. I’ll do this somewhat often if I really want a shoe, but don’t want to take the chance of them selling out before I can get them on sale. I still wear the shoe that I originally purchased.
ll even do it on Nike.com purchases. They’ll even tell you to do it in Nike chat if you ask for a price adjustment. They’ll just be like we can’t adjust the price since it’s over 30 days. But I what you can do is order a new one at the discount, and return the original.