What do you say when someone says welcome in?

I'm curious, what's the appropriate response when someone says 'welcome in'? Is it simply a polite acknowledgment like 'thank you' or is there a more specific response that's considered customary in certain settings? I'm particularly interested in how this might differ in professional environments or when dealing with clients in the cryptocurrency and finance industry. It's always important to make a good impression, so I'd like to know if there's a standard practice for welcoming someone in.