No. Reserving a copy of Win10 originally was about having the entire set of necessary files (or most of 'em, anyway) be downloaded to your machine ahead of time so you could do the update process with less wait time. Now Microsoft seems to be doing that as a part of GWX by default, angering any number of people who think it's a conspiracy of some sort.
If you have a Windows 7 or Windows 8/8.1 computer no product key is necessary and none is sent to you afterward. The upgrade process itself activates your copy of Windows 10 on the machine and it's licensing key.
What I recommend as the "safe upgrade procedure" is as follows:
1. Make a full backup of your existing user data and full OS system image of your Windows 7 or Windows 8 system using the backup software of your choice. In the event of something catastrophic occurring, which is unlikely, this is the easiest way to recover your existing system.
2. Run the Windows 10 Upgrade process. I suggest doing it either from GWX or from the "Upgrade this PC Now" option on the media creation tool page if your intention is to upgrade the PC you're currently on. If you really must have the Win10 ISO burned to disc or on USB, then follow the instructions regarding downloading it for upgrading PCs other than the one you're on. If you go that route you'll also need to go into BIOS or use the Boot Order panel to make your computer boot from the media you created to do the upgrade.
a. IF your system was a "well used" system, and particularly a well-used Windows 7 system (or even just a Windows 7 system, if you want to be anal-retentive about it) then immediately go to the Update & Security Settings, Recovery Pane and do a "Reset this PC" via the button. This forces a full refresh of the Win10 operating system. Use the "Keep my files" option, at least initially.
b. If you have a Win8.1 system, you can probably skip what was done in step 'a' for a Windows 7 system. If you notice that you're having irregularities within the first couple of days I'd give a Reset install a try then, but only if something weird appears to be happening.
3. Take the time to go through the Privacy Settings, all panes, to set things up as you'd like as far as device access and data gathering. I have shut down a lot of default access, but left system health reporting at "full" and there is not much traffic from that.
4. If you are on an internet connection that has data caps and/or peak and off peak usage periods and billing, definitely take the time open the Network & Internet Settings, WiFi Pane (which happens to be the default when N&I Settings open), then click on the WiFi connection (probably that you're currently connected to). Then scroll down below the list of WiFi connections to find the "Advanced Options" link. Be certain to throw the Metered Connections switch/toggle (I can't remember how JAWS announces it, because it's a new concept, maybe as a checkbox. It behaves the same way) to "ON." This prevents Windows Updates from automatically downloading via this particular internet connection without your express permission to do so. Otherwise, leave this set to "OFF" so that Windows Updates remain fully automatic. Also, in the Advanced Options is a switch/toggle entitled "Make this PC Discoverable." This serves the same purpose as the old "What type of network is this? Home/Work/Public" stuff did in Windows 7. Since both Home and Work networks in the old system made the computer discoverable by other Windows machines on the same network, that split has been eliminated. If you switch Discoverable to ON your computer is visible to others on the network and can share like you may have done in the past. If it's OFF it's the same as the former "Public" choice, and your machine is visible via WIndows to no other machine on the network.
5. Set up Cortana to your liking. I absolutely hate having Web results returned as parts of a Windows search, so I turned the "Search Online and include Web Results" setting off. I had no intention of using the digital assistant feature to interact with Cortana verbally, so I turned off the "Cortana can give you suggestions, reminders, ideas, alerts, and more" setting OFF, too. The digital assistant feature is quite remarkable, and I've played with it when setting up machines for others, but I know I won't use it. I also hate the fact that Cortana is stapped to Bing as far as searching for web results because I've just never warmed to Bing and won't at this point.