Steven,
To my understanding, both paid and unpaid itineraries needs to be persisted...."How long" and "to what extent" is ur call....for the exam persisting paid itineraries will suffice.Imagine u running a travel agency with 20 agents and an online customer
website. Bulk of ur transactions happen via travel agents. u would definitely want to know how much sale a particular agent(in seats/class/dollar value terms) made this season...this is ur primary business and hence makes sense to persist paid itineraries. It would also help resolving discrepancies, if any.
For intelligence/reporting format, sometimes unpaid itineraries are needed...u would like to track customers vis-a-vis their itineraries and indentify a preference
pattern for later marketing activies (newsletters and/or promotions).
where to store is again ur choice....could be db or flat file or an archive db...since the exam restricts ur choice of hardware choice, u might only want to persist the paid itineraries. But whatever u do, u need to mention it explicity in the assumption section. Hope that helps
Thanks
Sankha Das