Before using a money transmitting service, check whether it is registered as an MSB with the US Treasury Department's Financial Crimes Enforcement Network (FinCEN). FinCEN provides a website where anyone can check whether a company is registered: https://www.fincen.gov/msb-state-selector
    However, the inclusion of a business on the MSB Registrant Search web page is not a recommendation, certification of legitimacy, or endorsement of the business by any government agency.
Beware of financial services that do not ask for KYC information including name, date of birth, address, and ID before allowing you to send or receive money or cryptocurrency.
Understand that just because an app can be found in an app store does not necessarily mean it is a legal service and is complying with federal requirements.
Avoid using services that advertise themselves for illegal purposes.
Be cautious when using cryptocurrency services known to be used by criminals to launder their funds.

Using a service that does not comply with its legal obligations may put you at risk of losing access to funds after law enforcement operations target those businesses.