Need to affect Last Enter Value in viewstate in asp.net

my design is <table align="center" cellpadding="2" cellspacing="0" border="1" style="width: 900px; height: 100px;border: #04AFEF; background-color: White" id="Tabl"> <tr><td class="style1"><asp:Label ID="SalesNo" runat="server" Text="Sales No"></asp:Label></td> <td><asp:Label ID="Terms" runat="server" Text="Terms"></asp:Label></td> <td><asp:Label ID="SalesDate" runat="server" Text="Sales Date"></asp:Label></td> <td><asp:Label ID="CustomerName" runat="server" Text="Customer Name"></asp:Label></td> <td class="style3"><asp:Label ID="CounterName" runat="server" Text="CounterName"></asp:Label></td&g ...