Should i trigger a login or signup popup for "registered only features"?

I have a SPA which allows the user to act as an anonymous or as registered / logged in user (Free/Paying).

For better converasion rate & UX - what is the best flow? what is the user expectation in that case (while I don't want to tired those who pays and just need to login)

User clicks on feature which available only for registered users: 1. Show Signup popup or 2. Show Login popup

Thank you!