You have to pay the license for full version of Reliasoft design of experiment. I recommend you use alternative software like Minitab as it is much better than Reliasoft design of experiment in terms of analysis capability ...etc
Dear Prof Omar , thanks for your comment. I have the minitab but I do not know how to use it for the analysis . Can you be of assistance to me in explaining or sending materials that can help me use the software . I intend to use it for four factors with three replicate each