The answer to your question: what’s the most ram I can put into a MacBook? is 4GB of RAM can go into an Apple MacBook, if it’s the most recent model of Apple MacBook, or even a pretty recent model you can install 4GB of RAM into the two slots. To do this, you will need to buy MacBook ram in pairs, or single memory modules. There’s no real difference between the pairs and the individual memory modules except for the fact that some stores sell MacBook memory in kits, as opposed to individual pieces of ram.
With the MacBooks, there are 2 different ram types you should consider: PC2 5300 DDR so-dimms were the first ram modules made available for MacBook laptop computers, but as apple kept on releasing newer and newer MacBooks they changed the memory requirements to DDR3 ram which runs at 1066MHz and that is the memory type that all newer MacBooks require.
There’s a good chance your MacBook came from the factory shipped with just 2GB of memory installed wit 1x2gb in each available memory upgrade slot, so to upgrade to 4gb you will need to buy 2 2gb ram modules to buy ram for your MacBook computer
If your MacBook is new and released in 2010: 4GB of RAM is the best it gets.
If you have an older MacBook you want to upgrade, then chances are it’s maxed out already at 2GB but be sure to check your model and then ask one of my recommended memory stores to ask and double check your MacBook memory requirements.