Ask HN: How do you open source a SaaS with payment handling?

Hey all,

I'm building a web analytics tool that a few people are paying for at https://plausible.io. I claim to offer better privacy than Google Analytics, but I'd like to prove that statement by open sourcing the code behind it.

My only reservation at the moment is that the codebase includes the payment integration with Paddle (similar to Stripe). Are there any concerns with open-sourcing this code along with the main analytics code? If so, how could I separate these two concerns in code so I can open-source one while keeping the other closed?

Thanks in advance, Uku