Can I upgrade the RAM in a 2017 MacBook Air?

No. Apple soldered the RAM onto the logic board starting with the 2010 MacBook Air, and the 2017 model is no exception — it’s baked in permanently. If you bought the 8GB version, you’re stuck with 8GB for life. Third-party reballing is expensive, risky, and voids your warranty, so it’s not worth it. If you need 16GB, sell the 2017 Air and buy a used M1 MacBook Air instead.