With RAM, as we mentioned, you can ignore the 'minimum specs' listed on the websites of the major DAWs. Anybody who tries to run a multitrack Ableton Live session on a laptop with 4GB of RAM is braver (or more patient) than we are. That’s because RAM is effectively the short-term memory of your machine. With audio applications, particularly those involving lots of recorded audio, a higher amount of RAM means your audio playback is buttery smooth and glitch-free because the computer isn't having to 'grab' the audio from the hard drive each time it wants to play.
If you're buying now, with the next few years of use in mind, we'd suggest 8GB of DDR4 memory is the absolute minimum you should be looking for. Ideally, you'd want 16GB, as this will handle much larger arrangements, although there is a cost to this extra resource.
It's also worth investigating whether the laptop you choose can be upgraded with extra RAM in the future. Apple laptop fans won't have this luxury, due to their sealed chassis, but laptop PC users might.