Hy. how can I activate a second copy of FSX..... please!
You should have a key number (yellow) in the case.
If you lost it call.
https://support.microsoft.com/en-us/help/4051701/global-customer-service-phone-numbers
I have the key but I want to use the same key on an other PC.....is it possible?
No, they will only let you install it on one machine, one person.
Of course it may work but I doubt it.