With the Movie Edit Pro 17, when you purchase the encoder, you own the license for that encoder for the Movie Edit Pro 17 product, so you would not need to reorder unless you are putting the program on multiple computers, which is against the license agreement.
So in essense, you will not need to reorder, they will be available to you for the life of the program.
According to the license agreement you can only install on one system. That is a pretty common practice through out the software world, although there are some softwares that do have a multi-install license, they usually cost a little more.
I am not the authority on that though, you would want to contact Magix customer service to square away that information. This is just a user-to-user area.
Now, butcha...
You would need to contact Magix customer service to reactivate software.
You can contact customer service at 305-722-5810 or check out the LiveChat on the Magix support page.