Today, most consumer product companies and numerous B2B's shop for externally sourced technologies. One can typically discern their seriousness by whether they spend money to explore a technology beyond simple sample evaluation. It doesn't necessarily require a lot of money. if they're tapping into their budget in the context of a development agreement, this signals that there is more than a casual interest. When no money changes hands, and a technology provider is being encouraged to do additional testing at their own expense, this often indicates that there isn't yet serious interest.
To be clear, companies can be as patient as they choose to be when considering external technologies. Most are disinterested in making hasty decisions, especially if that decision can have a sizeable cost associated with it. Therefore, it is up to the technology provider to make the strongest possible case for his/her offering. It is also up to each individual technology provider to decide their investment tolerance for earning a customer's interest.
As parties increasingly enter into exploratory relationships to discern the basis for a technology-based business deal, it is important to be vigilant for evidence of real progress. Regardless of what is being said, money exchage tends to offer the most realistic indication of interest.