I bought Sam & Max series 1 a couple of weeks ago and for some stupid reason didn't save off the web page with the order details. (possibly 1 beer to many :P)
I thought that this would be fine and I would get an order confirmation by email but that never happened.. anyway I did download the episode 1 binary from the order page and was able to play (only took me 2 hours to complete it so I really hope that the whole series gives a little more challenge).
Since I never got a confirmation email I started to get worried about not being able to activate (or download for that matter) new games.
I actually purchased the Sam & Max collection without first registering and logging in on the Telltale Games website - registration and order takes place on Digital River for the actual order.
I sent an email a couple of days ago to Telltale but got no response so I thought I would register and raise it on the forums and am now happy to note that having newly registered the email address is already on the database related to past purchases and I can see my order number! :)
I think this means that I stand some chance of now being able to activate subsequent versions of the game but it would be really nice to know if we can also expect emails with download URLs when subsequent episodes of the game are released.