Is the cost linear in the decision variables? If so, use intlinprog. I assume that you have other constraints that you did not list, such as all variables are positive. All Optimization Toolbox™ solvers minimize; to maximize, use the negative of your cost function.
If the cost cannot be made linear, you can try ga or surrogateopt, which try to minimize nonlinear functions over integer variables.
MATLAB mathematical toolbox documentation