In the United States, any virtual currency exchange that operates and conducts business within the country must be registered and licensed with the Financial Crimes Enforcement Network (FinCEN) of the U.S. Department of Treasury. This regulatory body oversees and enforces anti-money laundering (AML) and know your customer (KYC) regulations for virtual currency exchanges to prevent illicit activities such as money laundering, terrorism financing, and fraud.

One of the most well-known and widely used licensed virtual currency exchanges in the United States is Coinbase. Founded in 2012, Coinbase has gained a reputation for being a secure and reliable platform for buying, selling, and storing cryptocurrencies such as Bitcoin, Ethereum, and Litecoin. The company is registered with FinCEN as a money services business and complies with all relevant regulations to ensure the safety and security of its users' funds.

In addition to Coinbase, there are several other licensed virtual currency exchanges operating in the United States, including Kraken, Gemini, and Bitstamp. These platforms have also obtained the necessary licenses and registrations from FinCEN to legally operate as virtual currency exchanges in the country.

By choosing a licensed virtual currency exchange in the United States, users can have confidence that their transactions are being conducted in compliance with regulatory requirements and that their funds are secure. It is important to do thorough research and due diligence before selecting a virtual currency exchange to ensure that it is reputable, trustworthy, and compliant with all applicable laws and regulations.