You can buy voucher credits in the Wi-Fi Shop. When you have credits, you can generate your own voucher codes from the credits.
1 free voucher costs 1 Voucher Credit up to 1 month expiration. Voucher that expire in 3, 6 or 12 months costs 3, 6, 12 Voucher Credits. You can generate your own vouchers within one year of the last bulk voucher purchase (across all locations). Pay per Use Vouchers cost 2 times more than Free Voucher credits.
Credits expire 1 year after purchase, unless you buy more credits within 1 year. If you do so, the expiration of ALL credits will be extended to 1 year from the date of last purchase.
Please note that there is no expiry on vouchers that you have already generated, those vouchers can be used any time in the future.