If you're writing an article about ways to make money, you don't list "robbery" or "kidnapping" as serious options. If you're writing an article about monetising software, you don't list techniques which abuse your users' trust (and which the vendor has banned) as options there, either.
And as the creator of a competing service that allows browser extension makers to take payments in their extensions without needing a backend server (https://extensionpay.com), I know from my users that making money from extensions is far from "impossible" :)
1. Is there a socially acceptable path to go from free to non-free?
2. How much can one reasonably expect to earn per user per month or year in your experience? (My extension is by no means mission critical but it solves a (simple) problem rather elegantly IMHO).
There's no way to tell for sure! It really depends on the value the extension provides, your market, exposure and reviews on the Chrome store, etc.
I can say that one of the extensions that uses ExtensionPay is a really simple utility that allows switching between recently used tabs in Chrome (https://chrome.google.com/webstore/detail/alt-%20-q-switch-r...) but users love it and it makes a surprising amount of money!
But all that is ultimately speculative for your extension. One reason I made ExtensionPay was to lower the barrier to making paid extensions enough so instead of speculating you could just try it out and see what happens!
> 1. Is there a socially acceptable path to go from free to non-free?
From what I've seen there will be a very loud but very small minority of users that will get angry and leave bad reviews. I think if you try to make these users happy (maybe by giving them free access?) and let the others know why you're asking them to pay then it will go alright. Here's what I wrote about charging for a previously-free JavaScript library: https://github.com/Glench/fuzzyset.js#license
Didn't know about the Publish API, thanks for the suggestion will check it out.
I sometimes dream of what a difference it would make if I could monetize it, but I see no viable path there.
