as long as they paid with a credit card or your added a customer on cash transactions all records are there from your first transaction.

I'm a service company. I wanted to know how much abc company spent on labor, parts, and anything else. 

from this link, you can see all their past transactions, and click on each to see the details, but it does not break it down into individual items.

you can go here https://squareup.com/dashboard/sales/reports/item-sales and export the file detail.csv and open that in your spreadsheet program.  you can then sort by the customer field and then sort by the item field.  a couple formulas to get totals and you should be all set.

Then perhaps that could be a simple feature request.