ARD 3.4 upgrade - asks for new serial ? ?

I was having trouble observing another Mac on my LAN today, so I upgraded ARD

to version 3.4.

Now, when I open the program, it asks me for a serial number. I entered my 3.3

serial but it won't accept this.

Where do I find this number ?

It says that it can be found in the "welcome pack" but where is this ?

I upgraded by Software Update and all I got was an install of the app.

No other documentation at all.

Would appreciate any help given.

TIA

Chris