Extended Warranty Question

I know that within the factory warranty, in order not to void the warranty you have to make the regularly scheduled maintenance from the trip computer. So say you purchase the extended warranty platinum, but don't buy the maintenance extended warranty and you opt to get the maintenance done at a BMW Indy. How do you prove you were doing the maintenance (so you don't void the platinum extended warranty), if you get it done at the BMW Indy?

Extended Warranty Question