Dumb Question

Hi,

So i have a noobish question to answered, about software license keys because I bought dxtory today and it was a single user key, and what I'm wondering is if I ever have to reset my computer or anything like that won't that mean I won't be able to use the key again? OR could I put it on a USB thumb drive which I have. Sorry if it is a stupid question just wondering 

Thanks.

you should be able to re-use it. it just means you're not supposed to share it at all