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 product_id (in the product settings / API). Every buyer now gets a key on their receipt.
Verify a key
