Gas lift allocation can be modeled as a nonlinear programming problem in which adjusting optimum gas injection rates and compressor pressure maximize the oil rate or other objective functions. This study describes a nonlinear programming approach to maximize daily cash flow of some gas-lifted wells in an uncertain condition for oil price. First, some solution points of each well are obtained by employing a production simulation software. Then, by use of nonlinear optimization, a model is developed for gas lift performance in each well. Then these functions are used to develop a model under capacity, pressure and other real constraints for the cash flow of production from these wells. Oil price is assumed as a triangle risk function in this model. Results show a significant increase in cash flow in comparison with old case due to appropriate gas injection parameters. Sensitivity analysis on this problem shows that oil price, compression cost and water-oil ratio variations should be considered in the long term optimization.