If you sell a desktop app on Gumroad, it hands every buyer a license key. But Gumroad stops there — checking that key inside your app is entirely up to you. Here's how to do it properly in Node/Electron, plus the three traps that catch almost everyone. We'll use gumroad-license-lite, a tiny, zero-dependency, MIT-licensed helper (you can npm install it or just copy its ~120 lines). Turn on license keys in Gumroad On your product, enable "Generate a unique license key per sale," then grab your pro