Fascinating. Terra is attempting to establish such a system that is separate from monetary gain. To instead rely on the combined effort of the entire civilization towards a common goal. It has been difficult, but I believe that it will one day be possible.
However, we still use credits.

[Spock looks around for a moment then looks at Miss Mizuno]

.... I must thank you Miss Mizuno for your assistance, but I would be remiss to keep you any longer. Perhaps we shall meet at a later date?