Used X Is It Safe To Buy Flight Simulator X Used On Ebay?

Is it safe to buy flight simulator X used on ebay? - used x

I have some questions.

Has to be online in order for Flight Simulator X register

If I uninstall the game, I'll be able to play on another team?

If so uninstall how, because Microsoft knows that unregisterd.

If I buy on ebay Flight Simulator X uses, but if you buy on my computer, since the number of licenses