max memory is dependent sa board (usually on the number of slots it has - can be 2, 4, 6) since lower end boards will only allow up to say 8GB, or 16GB while the higher end ones can go up to max of 96GB (6 sticks of 16GB but mahirapan ka maghanap ng single stick na 16GB)
mostly sa mga laptop pag nakalagay sa page ng manufacturer na up to a certain amount lang, yun lang talaga since its a motherboard limitation (wala ka magawa dito other than replace the board itself and in laptops, its better to just buy a newer one than to replace a motherboard). although there have been some cases that people have been able to fit more than what is indicated. example, sabi ng manufacturer max of 8GB lang siya (2 slots), but you can actually fit 2 8GB sticks so you can go up to 16GB, pero this is rare, mostly pag sabi ng manufacturer up to 8GB, hanggang dun lang talaga yan
in my case, my laptop has 8GB installed, the manufacturer (MSI) says a max 16GB upgrade is possible BUT since it has 4 slots, you can actually go up to 32GB (if you replace the 2 pre-installed which is in another slot. yung slot na nakikita mo pag buksan ang likod na dalawa is for the expansion slots only, hindi mo makita ang pre-installed unless buksan mo buong laptop)