HOW TO RESTRICT NO OF USER REGISTRANTS IN A DAY IN ASP.NET

There is too many way's to done this task.

But i want to suggest , you could use WCF Service in this scenario

You can check the database if no of registration exceeds 10 you can simply display message. Please try it.

string check="select record from table";
SqlCommand cmd=new SqlCommand(check,con);
SqlDataReader dr=new SqlDataReader();
dr=cmd.ExecuteReader();
if(dr.Count>10)
{
MessageBox.Show("Limit Exceeded");
}