A Washington State marriage license is not valid for use outside of Washington State.
If you plan to marry in another state or country, you will need to apply for its marriage license and comply with their laws for getting married.
In order for your marriage to be recognized in Washington State as a lawful union, you must be married according to the laws governing the location at which you were married, including the completion and filing of permanent marriage records, and it cannot fall within the prohibited marriages listed in the Revised Code of Washington (external link).
Obtaining certified copies of the permanent marriage record, including certified translation into English, if necessary, will prove that you were lawfully married in that location. You can, but are not required to, record that document as a safeguard against loss with King County Records.