No, you do not.
But, it’s very hard to answer which states you do need to register your company in.
Our advice is as follows: You should be registering your company in each state that you’re lawfully “conducting business in”, as each state individually defines “conducting business” in their state.
It’s really hard to give you a set of rules for all states. What we can say is, if you’re “purposefully availing yourself” of a state, you’re doing business in the state. What is “purposefully availing yourself?” If you have a base operations in a state, that’s probably “purposefully availing yourself.” So would having W2 employees in a state. And, singling out a state for marketing purposes. Another general rule is, if 25% or more of your income is coming from one particular state, then you’re probably doing business in that state.
Each company is different, though, and just because you’re a consultant and a big client is in a state for 6 months, then you’re off to another state, probably doesn’t rise to the level of “conducting business in” a state. You really need to consult with a locally licensed business attorney to help you understand what a specific state’s requirements are, and whether your business falls within those requirements.
All we can do at L4SB, is provide general guidance.