Here's how to move to the new API on Azure
Register and Create a new Key at https://datamarket.azure.com/account/keys
Register for Bing Search (web only) https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65
Download .NET C# Class Library from https://datamarket.azure.com/dataset/explore/getproxy/8818f55e-2fe5-4ce3-a617-0b8ba8419f65
Add the BingSearchContainer.cs to your project

<asp:Repeater ID="RepeaterBingResults" runat="server">
<ItemTemplate>
<a href="<%# DataBinder.Eval(Container.DataItem, "Url") %>" target="_blank">
<%# DataBinder.Eval(Container.DataItem, "Title") %></a>
<div style="font-size:x-small"><%# DataBinder.Eval(Container.DataItem, "Description")%></div>
</ItemTemplate>
</asp:Repeater>
In Your search button Click Event add in the following code
BingSearchContainer bing = new BingSearchContainer(new Uri("https://api.datamarket.azure.com/Bing/SearchWeb/"));
bing.Credentials = new NetworkCredential("YourAccountKey", "YourAccountKey");
DataServiceQuery<WebResult> results = bing.Web(RadTextBoxSearchText.Text, "en-gb", "strict", null, null, null, null, null);
Then bind your repeater
RepeaterBingResults.DataSource = results.Execute().ToList();
RepeaterBingResults.DataBind();