Transaction History

We produce trade shows and conferences. We want to use ZOHO CRM to manage our ongoing contact with our customer base via phone, email and postal mailings. A key element to this plan is importing purchase history with each customer record (or appending it after the customer records are imported). We have roughly 60,000 transactions (actually registrations to one of our events) associated with 10,000 customers that we want to be able to include with the customer records. Note that we want to associate each registration (date, type, demo question responses) with the Contact but also be able to see it by Company. Multiple people often come from one company and some people have come for several years. How is the best way to include and associate this registration data? Thank you!