How many days can I redeem my Blizzard Balance Card?

Good day! I bought this USA Blizzard balance card online last night but I can’t redeem it. It says that I can’t claim the code in my country/region(Asia). I’m planning to sell it but I don’t know until when could I sell it so my question is, does the balance card have certain number of days where it should be redeemed? If so, how many days? Thank you in advance!