Help about buying download

[Geno]

Hello Im away from home at the moment with my labtop. And Imma be here for a while and I really want to buy punumbra(download). I use my desktop for gaming. Is there a way I can buy the download on one computer and play it on another?

[Xanthos]

Buy it off of steam.
You download it as many times as you wish after purchasing.
BUT, you have to type in the password/username before playing to prove it's you.

[Geno]

Thank you so Much!