How long does one need to stay in the US for that not to hold ? I lived there for one year, and bought a lot of stuff in the US for personal use (like clothes)

How long does one need to stay in the US for that not to hold ? I lived there for one year, and bought a lot of stuff in the US for personal use (like clothes). When I moved back to Europe, I just moved everything with me without paying any VAT. I was worried that they would make me pay VAT from socks and underwear to laptop, phone, and everything. Asked about it, and was told that I didn't had to pay anything.