Thundercat's playing on this Mac Miller song is groovy, understated, and memorable. There's really just one bass line (in C# Natural Minor) throughout the whole song, but there's one really attention-grabbing fill.
Learn the bass line and that fill here and download the free drumbeat below.
Mac Miller - What's the Use?
How To Memorise A Bass Line
Bass lines are easier to remember if you know patterns really well.
The key is C# Natural Minor so make sure you know that scale inside out.
What you will find is that bass lines conform to these patterns - as they come from scales. A great bass line is a scale played with cool techniques, tone, feel, and rhythm. Make sure you familiarise yourself with these elements of music so that you can blend them together to make up your own lines as well as learn songs easily.