Steam Region Restrictions

no, games from other regions cant be activated (steam will say something about regions during activating)
if u activate game - its your - play it free

if it's an old game it's only the region tag in its name (fallout new vegas has the same thing), the game is the same unless it's censored in those countries.

The key must be old, they come with the tag along but they are later made ROW is the reason you are able to activate it. If a key is region restricted, it won't activate unless you are from same region or using a vpn [ against steam tos] .