我可以使用无边框vpn优惠券进行现有订阅吗？
通常，无边界vpn优惠券适用于新用户，不能应用于现有订阅。
for most cases, only 1 coupon can be used for each new borderless vpn subscription. the borderless vpn checkout page doesn't usually allow more than 1 code to be applied at the same time.