I bought from stacksocial the office Pro 2021 and it worked perfectly until I reinstalled windows 10 due to a motherboard failure. After downloading the Office Pro 21 there was a message that the office Pro 21 was installed in "another computer" and it didn't activate at all.
The customer support of the Stark Social gave advices that did not work, they even offer to send a new code (It never happened). After 2 weeks trying everything, I called MS office customer support (for pro version is available only from Monday to Fridays,. Home version all the week long) and they send a program to erase all fail downloads of office... didn't work either. On a 3er or 4th call to MS office customer support they said that my office version didn't exist and should go back to the seller. This time, a month later, Stark Social support team did´t even answer the emails.
The temporal solution was to install my oldie office 2000 that works fine in win 10.
Two months later I when back to see if I could make the program work again.
The main problem was that this version of office pro 21 (is only for one computer) is hooked to your MS live account. To reactivate Office (any version), open an Office app like Word, Excel, PowerPoint and sign in with your account the office ... Presto! it works again.
Neither customer support had a clue on how to activate the office 2021 in "another computer".
Now It works fine! No issues! I recommend the product only because is legit.