Generally employees' salaries are the biggest expense in almost every startup and at every stage. Hence the saying that "overhead walks on two feet"
Founder living expenses.
I've done quite a bit of initial patent work for startups that paid me with seed funding. Its important to get your patent applications filed early, so you can exclude your competitors from entering into your space.
It pays your founders life expenses. It usually last 6 months so they can build their MVP, get some initial traction and go after a larger round without starving.