Today's Apple laptops have RAM soldered in. I just had a quick look at their site and unless I have missed something I believe that if you want more RAM than offered as standard you must specify that when you order what you want.
Many mountains were made out of molehills on the topic of soldering RAM, but it is a sensible reliability decision, and it also allows Apple to design their products to tighter tolerances, allowing for a thinner, lighter design.
As I said above, most except the very basic Apple Mac Book Pros now come with 8GB of RAM by default. Which is normally more than enough for your average Joe.
But as I always say, if you can afford more RAM, you should buy it, so if you can afford to bump up to 16GB then its a cheap way to afford yourself extra peace of mind.
If there is any prospect of you ever wanting to do more intensive stuff, such as running Windows in a virtual machine, then of course, bumping up to 16GB is no longer an option, but a must !