Grosse Pointe Woods
"When you take the buy goods action, treat your hold value as two higher than its current value"
My question is / How long does your hold value stay increased?
Just like every other Advisor bonus, you use it on that turn. In this case, think of it as literally smuggling. The smuggler showed you where you can stash the extra goods when you buy goods while he is active. You can't do it while he is not the active advisor. So buy your 4 goods, stash them and then later unload them. Your hold goes back to what it normally is until you use him again.