They're not highly visible, but there's quite a few paid extensions. Chrome used to have payments built into the Chrome Web Store before they deprecated it a fe

They're not highly visible, but there's quite a few paid extensions. Chrome used to have payments built into the Chrome Web Store before they deprecated it a few years ago (https://developer.chrome.com/docs/webstore/cws-payments-deprecation https://developer.chrome.com/docs/webstore/cws-payments-depr...). You've always been able to add your own payment system. I sell a freeium extension with payments going through Paddle (I guessed Google might deprecate their payment system so didn't risk it!). Gumroad and Lemon Squeezy are other examples you could use, where they both have simple license key checking web APIs.