Can Lemmy be used privately?

[curiosport]

Please correct me if I am wrong about the following ideas I have about Lemmy:

1. I can install it on a separate self-hosted server.
2. I can make my Lemmy site 100% private and only accessible with a paid membership.
3. I can create invitation codes for others to use and sign up.

[dessalines]

1 is possible. The first part of 2 is, but not paid. 3 isn't either.

[curiosport]

Thanks for your answers, and if I implement myself a payment system for my private community, won't I incur in any violation with your licenses or something like that?

[dessalines]

You must publish any changes you make to lemmy's source code publicly. That doesn't preclude you implementing payment systems in some way.

[curiosport]

How should I publish that? As a fork? As a pull request?

[dessalines]

Fork is fine, as long as it still has the same licence.