Spin-to-charge conversion using the inverse Rashba-Edelstein effect is measured in the 2D electron liquid existing at the interface between LaAlO3 and SrTiO3. The effect is found to be larger than in the highly Rashba split Bi/Ag interface which we attribute to an amplifying effect due to a long carrier's momentum lifetime. The explanation is supported by temperature measurements and the Rashba field is also shown to be anisotropic in the interface plane.