Before You Purchase (Fetch Your Machine Code)
For users that have already installed Explorer or Instructor: Before you purchase or renew an annual subcription to the Professional or Enterprise Editions of Explorer or Instructor, you will need to fetch your machine ID by using the menu command Help-->Get Machine Code, and then paste the code into the Windows clipboard. When you are at the store, there is a textbox on the purchase page to enter the Machine Code.
Never installed Explorer or Instructor? If you have not installed the free versions of Explorer or Instructor, then you will need to download and install the free version of Explorer or Instructor in order to obtain your Machine code (e.g., Help-->Get Machine Code).
Ready to Purchase (Requires Your Machine Code)
To purchase a Professional or Enterprise Explorer subscription, go to the Explorer Store
To purchase a Professional or Enterprise Instructor subscription, go to the Instructor Store
(Note: your purchase will not be successful if the Machine Code is not provided on the purchase page).