Once you have received your approved US.. travel visa, you will need to enter the United States within the specified period of time in order to maintain its validity. Once you arrive in the US, you must abide by all local laws and regulations and ensure you do not overstay your visa. Additionally, you may need to apply for an extension of your visa if you wish to stay in the U.S. longer than what was originally approved. Finally, once your visa expires or you decide to leave the U.S., you must depart within the designated time period or risk facing legal consequences.