this is a example i made
you can't use this keygen for a game or something but if you made it so you can it use for your own program 
this is a keygen with 16 letters
Code:
Dim objRandom As New Random
Dim number As Integer
number = objRandom.Next(1, 4)
Dim number1 As Integer
number1 = objRandom.Next(1, 4)
Dim number2 As Integer
number2 = objRandom.Next(1, 4)
Dim number3 As Integer
number3 = objRandom.Next(1, 4)
Dim number4 As Integer
number4 = objRandom.Next(1, 4)
Dim number5 As Integer
number5 = objRandom.Next(1, 4)
Dim number6 As Integer
number6 = objRandom.Next(1, 4)
Dim number7 As Integer
number7 = objRandom.Next(1, 4)
Dim number8 As Integer
number8 = objRandom.Next(1, 4)
Dim number9 As Integer
number9 = objRandom.Next(1, 4)
Dim number10 As Integer
number10 = objRandom.Next(1, 4)
Dim number11 As Integer
number11 = objRandom.Next(1, 4)
Dim number12 As Integer
number12 = objRandom.Next(1, 4)
Dim number13 As Integer
number13 = objRandom.Next(1, 4)
Dim number14 As Integer
number14 = objRandom.Next(1, 4)
Dim number15 As Integer
number15 = objRandom.Next(1, 4)
Dim letter As String
letter = ""
Dim letter1 As String
letter1 = ""
Dim letter2 As String
letter2 = ""
Dim letter3 As String
letter3 = ""
Dim letter4 As String
letter4 = ""
Dim letter5 As String
letter5 = ""
Dim letter6 As String
letter6 = ""
Dim letter7 As String
letter7 = ""
Dim letter8 As String
letter8 = ""
Dim letter9 As String
letter9 = ""
Dim letter10 As String
letter10 = ""
Dim letter11 As String
letter11 = ""
Dim letter12 As String
letter12 = ""
Dim letter13 As String
letter13 = ""
Dim letter14 As String
letter14 = ""
Dim letter15 As String
letter15 = ""
If number = 1 Then
letter = "A"
ElseIf number = 2 Then
letter = "Q"
Else
letter = "C"
End If
If number1 = 1 Then
letter1 = "B"
ElseIf number1 = 2 Then
letter1 = "S"
Else
letter1 = "D"
End If
If number2 = 1 Then
letter2 = "R"
ElseIf number2 = 2 Then
letter2 = "S"
Else
letter2 = "L"
End If
If number3 = 1 Then
letter3 = "N"
ElseIf number3 = 2 Then
letter3 = "K"
Else
letter3 = "M"
End If
If number4 = 1 Then
letter4 = "N"
ElseIf number4 = 2 Then
letter4 = "K"
Else
letter4 = "M"
End If
If number5 = 1 Then
letter5 = "L"
ElseIf number5 = 2 Then
letter5 = "K"
Else
letter5 = "P"
End If
If number6 = 1 Then
letter6 = "N"
ElseIf number6 = 2 Then
letter6 = "F"
Else
letter6 = "G"
End If
If number7 = 1 Then
letter7 = "R"
ElseIf number7 = 2 Then
letter7 = "T"
Else
letter7 = "Y"
End If
If number8 = 1 Then
letter8 = "U"
ElseIf number8 = 2 Then
letter8 = "Y"
Else
letter8 = "U"
End If
If number9 = 1 Then
letter9 = "N"
ElseIf number9 = 2 Then
letter9 = "F"
Else
letter9 = "G"
End If
If number10 = 1 Then
letter10 = "B"
ElseIf number10 = 2 Then
letter10 = "V"
Else
letter10 = "F"
End If
If number11 = 1 Then
letter11 = "T"
ElseIf number11 = 2 Then
letter11 = "O"
Else
letter11 = "K"
End If
If number12 = 1 Then
letter12 = "G"
ElseIf number12 = 2 Then
letter12 = "H"
Else
letter12 = "H"
End If
If number13 = 1 Then
letter13 = "T"
ElseIf number13 = 2 Then
letter13 = "R"
Else
letter13 = "S"
End If
If number14 = 1 Then
letter14 = "W"
ElseIf number14 = 2 Then
letter14 = "S"
Else
letter14 = "X"
End If
If number15 = 1 Then
letter15 = "S"
ElseIf number15 = 2 Then
letter15 = "X"
Else
letter15 = "F"
End If
Label1.Text = "Key : " & letter + letter1 + letter2 + letter3 & " - " & letter4 + letter5 + letter6 + letter7 & " - " & letter8 + letter9 + letter10 + letter11 & " - " & letter12 + letter13 + letter14 + letter15
because some people don't get it i will tell what the point of this
My point was to make a validation keygen ... i have only no validation program
maby i will make it later
if i help you tnx me xD
this is infact a really simple code