I'm not sure I understand what the salesperson is telling you.
If you don't pay for something and it hasn't been driven or registered, it can't depreciate. Are they asking you to sign a lease, pay for the closing costs and start making payments before the car is delivered to you?
If that's what they want you to do, scratch that. Talk to the manager. Put a refundable deposit on the car (all you would lose is the minimal interest they're paying at the bank) and then sign the deal. It has to be refundable by a certain date because the car might not come in or some other factor out of your control might cause a need to change the deal. Make sure an out date is in the deposit contract.
If you're seriously thinking about leasing, you should buy the software. It will pay for itself because you'll negotiate a better deal. Everything is negotiable about a lease regardless of what they tell you. You just have to know what your talking about.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition