If I factory reset my PC, will Dorico save my projects upon reinstallation? Also, will it count as a separate device and only let me have one more device?
You will need to make sure you back up all your Dorico projects to another device, e.g. a removable hard disk or USB flash drive. (You should do this anyway! Never rely on a single hard drive for data that you can’t afford to lose, whether they are Dorico projects or indeed anything else.)
You might also want to back up your Dorico configuration, which you can do by backing up the folder:
%APPDATA%\Steinberg\Dorico 4
If you’re simply reinstalling your operating system rather than changing any components in your machine, then you should find that when you come to reactivate the software, it is recognised as the same computer as before. But to make doubly sure everything works properly, before you reformat your computer, run Steinberg Activation Manager and click the Deactivate button, which will tell our servers that you’re no longer running the software on that computer.