The max RAM on this should be 64GB as that’s what the CPU supports. There shouldn’t be any other limitation despite what the manufacturer says, provided there are 2 accessible SODIMM slots.
To achieve 128GB, you would have to have 4 SODIMM slots which this laptop certainly does not have.
First, thanks to JDM for the info. I haven’t opened one up, but I did find a post on Reddit where another owner mentions adding an additional 8 GB SODIMM, meaning this does have at least one memory expansion slot:
And as for preferred pay method, Paypal is my preferred payment for stuff over the internet.