You simply need time in the field experience with these entities and the managers within them. It is pretty likely you were dealing with mid-level managers at best. VP titles in F500 companies are handed out like candy; most F500 VPs don't have signing authority for more than a few K per month, at most. A good sales person in the situations you described would have worked in qualifying questions into those conversations. How many people reporting to you would also benefit from this solution? Can you work this into your budget now or shall I work with you on justifying it into the next budget cycle? And so on.

The primary reason you didn't hear anything back is because these people, if they had any signing authority at all, are used to sales people pushing the deal along, and being the passive partners of the deal, no matter how enthused they were at the beginning. It is normal to see lots of initial excitement, followed by silence to repeated daily/weekly calls/voicemails/emails/letters/gimmicks for weeks/months/year, then a mad rush to purchase in just a week or two. I would go into details of why it generally works this way, but it would make an already too-long reply execrable.

Your description of what you were pitching was too vague for me to tell for sure, but the general rule of dealing with those licensing agreements is to get a company counsel to talk with you and express what their concern is that prompts such an agreement/clause, then in a friendly manner suggest alternate wording that protects that specific interest while not infringing upon your interests. Generally speaking, once you are exchanging legal/purchasing/contracts paper, F500 folks cop less "my way or the highway" attitude, and are more willing to meet you halfway if you are reasonable and negotiate friendly-like. Hire an attorney to teach you the wording you want to protect your specific interests if you are unsure of how to make the changes.

For some classes of software, you can separate out the R&D to a standalone company, designate yet another company as a retailer/distributor, and sell only licenses through the retailer/distributor. The R&D company will not sell direct, "as policy" (if pressed, just say the R&D team just doesn't want to get into the retail/wholesale side of the business, preferring someone with the appropriate skillset handle that for them). Anyone else who wants to be a retailer/distributor, has to have the appropriate skillset to support the product. It just so happens that only one company in the world so far can do that. As far as the F500 is concerned, you are now a third-party selling and supporting licenses, not the actual product itself. There is an exclusion of the "grab everything we can" clauses in every purchasing contract I've seen for third-party licenses. This is because the F500's realize Microsoft won't sell them Office (for example) if they made a grab for IP via purchasing of licenses.

I've said this before, but it bears repeating. Hacker effectiveness follows a power law, and business savvy does as well. You denigrate and ignore the high-effectiveness business people at your peril, as you have found out. Just because the majority of business people are mediocre like the majority of programmers, does not mean you can do without them.