Here are some features of Google adwords Coupon US $100 :-
This vouchers can be used only time on New accounts
You can use one only one coupon in one ad account
Must be applied within 14 days of account creation Adwords
Only valid in US country billing.
You need to add the payment method in account like credit card before redeeming this voucher code.
You need to spend the specified amount within 31 days of entering coupon code.