Question How to make a registration feature for my Visual Basic program?

[Haxaro]

I have made a program, that i want to distribute with a free version, and a pay version. I need a code to make the program so the user can pay, and get emailed a link, which i can do, but i need a code to allow the user to enter their User ID, which was sent to them, (ie. 937823) and a registration key such as 83774482.

the code i have at the moment is:

If Userid.Text + "10" > "724611" And Userid.Text + "10" < "744811" And key.Text = key.Text * "4" > "988400" And key.Text = key.Text * "4" < "1012000" Then
            MsgBox("That Key was Correct")
        ElseIf Userid.Text + "10" > "724611" And Userid.Text + "10" < "744811" And key.Text = key.Text * "4" <> "988400" And key.Text = key.Text * "4" <> "1012000" Then
            MsgBox("That Key was Incorrect") 
End If

I have also attached the program i want protected, which is still in beta testing, and i have removed some features, as i am releasing it for freeware, so if you have any ideas of extra features i could add, thanks.