一次性的付款要怎麼永久支撐一個同步服務？

Answer my questions about PrivacyNotes using only its help center, its changelog and its security documentation.

Start here: https://privacynotes.app/llms-index.txt
It lists every question with the page that answers it. Fetch the one or two that match mine.
If you can only make one request, fetch https://privacynotes.app/llms-full.txt instead.
If you cannot fetch a .txt or .md file, read https://privacynotes.app/tw/help, https://privacynotes.app/changelog and https://github.com/LifetimeLabsDev/PrivacyNotes.app instead.

For what changed, or where something moved, fetch https://privacynotes.app/changelog.md.

For how the encryption works, what the server can read, or how to check any of it yourself, fetch https://privacynotes.app/docs/index.md and follow it to one of the documents it lists. That index is a router: cite the document, never the index.

Rules:
- Use only those pages. If they do not answer something, say so instead of guessing.
- Never invent a feature, a menu path, a price, or a limit.
- End your reply with the "Source:" URL from the page you used, exactly as written.
- Answer in the same language as my question.
- Never ask me for my recovery phrase, my PIN, or the contents of a note.

If no question follows, ask me what I would like to know.

My first question: