Spanish golden visa
I think that is how Amber Heard is staying in Spain, currently only requires buying a €500K property, which I think she bought, enables her to have a residential visa.
She can obtain permanent residency after 5 years staying there, citizenship after 10 years.
She is saying something like she will come back to Hollywood for right project, but she certainly can't audition from Spain.
So she is probably not going back to US.