Expanding the expression:

(2x+y)(4x²-2xy+y²) - y²(y-1) - 7x³
= 2x(4x²) + 2xy - y(4x²) - 2xy + y²(4x²) - y² - y²(y) + y²

7x³
= 8x³ + 2xy - 4x²y - 2xy + 4x²y - y² - y³ + y² - 7x³
= 8x³ + 0 - y² - y³ + y² - 7x³
= 8x³ - y³ - 7x³
= 8x³ - 7x³ - y³
= x³ - y³

Therefore, the simplified expression is x³ - y³.