I have been trying out Ableton Live for the past few weeks, and last night decided to buy it. (I should write a separate article on the virtues of full-featured but time-limited demos). The product registration process for Ableton Live is very easy to use, and I think more commercial software vendors should adopt this process.
After making the purchase, you simply start up Live again, and instead of clicking the button to get a trial usage authorization for the demo, there's a link to the Ableton web page to authorize the product. Since I was still in the same browser session as when I just bought the product, I was still signed in and it was able to determine quickly that yes, I had in fact just paid for a copy of the product, and it gave me a link to use to authorize my copy of Ableton.
Clicking on this link took me to a file type that opens directly in Ableton Live (you know when you get that Save / Open with dialog when clicking a file - this one had pre-selected "Open with Ableton Live"). Opening the link authorized my copy of Live.
This was fast and easy. No need to wait for the box to arrive, no need to cut and paste auth codes or type in a lengthy CD key. They have found an easy way to link the fact that I paid for the software (their web site) with the software that is installed on my computer.