I can't upgrade the memory on my laptop - it has 8 GB soldered directly onto the motherboard.
I am currently on Windows 10 but I suppose I will eventually have to upgrade it to Windows 11 unless I buy a new machine. I don't have any plans to at the moment because this one is pretty good apart from having a dodgy left speaker.
I think a bigger and faster SSD would be a worthwhile investment though. The current SSD is only 256 GB and is about 2/3 full. It probably isn't as fast as it could be either...