Can I upgrade soldered RAM in my laptop?

No, you cannot add or replace soldered RAM because it’s physically attached to the motherboard. If your laptop has soldered memory, you’re stuck with whatever it came with. Some laptops have a mix of soldered and SODIMM slots, but if both are soldered—common in ultrabooks—16GB is your max. Upgrade before you buy next time or look for a model with replaceable RAM.