Selling software items from Order Management

We want to sell software items as service items where we want to capture start, end dates for the software items through Order Management responsibility.

So when we are trying to enter start,end dates for the services it is asking for the product reference such as sales order number, customer product.

But here we want to sell only software items as service items which are not associated to any shippable products.

How this  can be mapped in Oracle..