Yes. Amazon for example was a normal merchant for years and did not need a money-transfer license.  However, as soon as they decided to open a marketplace for 3rd party stores, they required licenses.  And they got them.<p>The rule is simple - if you take and hold on to customer funds, you need to be licensed for money transfer in all the states you operate in.<p>Today, a few services like Braintree and Stripe offer a middle ground solution.  Essentially, they will open an escrow account for your merchant customers, and you move any money your holding into the escrow.  They will then hold the funds until you release them.  This approach is clever, but still a legal grey area.