Hi,
The integration between HikaSerial and HikaShop is more than a custom buy a product. There is not feature which can generate a serial on the first order.
At this moment, I don't think that HikaSerial will be the best solution because if you just want to generate an HikaShop discount coupon on the first custom order, you can do it thanks to a custom plugin.
HikaSerial can provide you a good coupon code generator but HikaShop can already generate coupons (and you can use a Joomla function to generate a coupon code, with the Joomla password generator).
So I think the best solution for you is to develop a little HikaShop custom plugin.
www.hikashop.com/en/support/documentatio...r-documentation.html
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.