The short answer is "no". The high-level concept of AGPLv3 is to prevent someone who'd like to re-sell the OSS company's features (billing in our case). For instance, let's say you're a vertical SaaS like Mindbody, selling software to yoga studio owners so that they manage their business: scheduling, payment, and billing. If you use Lago to build your own billing feature (and sell it as part of your product), you'd need to either buy a commercial license (we call it "Lago Embedded") from us OR open source your code. Let me know if you need more clarifications!

> OR open source your code

That is - offer your code to your customers under the agpl, not necessarily back to Lago or the community. But, since your customers get the code under AGPL, they in turn are free to distribute it. So, in practice, going that way - it generally makes sense to just open it up, and contribute back directly.

(imagine your only customer is IBM, or some other big company - they might not care/have an interest in re-distribution of the AGPL code - so you could be compliant (offer source to IBM) - but effectively closed off from the community).

As far as I understand it there's no legal precedent, so we're not completely sure. Some say calling an api means it's part of your application, meaning you need to open source your app. Some say that that's not the case. I think this unknown is why the license is banned in some companies.

I think what matters more is how the creators of the software intend the license. In case of Lago it's clear they want you to use it this way, and AGPL is only really meant to restrict businesses that want to fork it and start a proprietary billing service.

That's on point. A "proprietary billing service", or a service that includes billing in the value proposition in general: whether you're a vertical SaaS, an accountingtech, or a payment processor.

If you don't change the source code of Lago, then you don't. Having your app call it via REST, for example, is fine.