Hi,
HikaSerial will create a subscription once the status of an order changes to confirmed or shipped. This can be changed with the "Assignable order statuses" setting of HikaSerial's configuration page:
www.hikashop.com/support/documentation/1...ation.html#main_main
HikaShop will generate an invoice once the status of an order changes to confirmed or shipped. This can be changed with the column "invoice", in the System>Order statuses menu:
www.hikashop.com/support/10-documentatio...rstatus-listing.html
An order created with a positive total amount, and then paid by the customer, will have its status changed to the "verified status" configured in the payment method settings.
An order created with a total amount of zero will have its status changed to confirmed by the "HikaShop Free orders validation Plugin". This plugin will use the status selected under the "Confirmed" column of the System>Order statuses menu.
So, you could create an extra status "free trial", selected it under the "confirmed" column in the System>Order statuses menu, and select it in the "Assignable order statuses" setting of HikaSerial's configuration page, without selecting it under the "invoice" column in the System>Order statuses menu.
That way, the order of trial products (with a price of zero) would generate an order with the status "free trial" which wouldn't generate an invoice, but would still generate the subscription in HikaSerial.