first, you should be aware that you hold all the cards. You have no obligation to do or sign anything with any third party. The fact that they approached you simply indicates their reluctance to use a product without ownership. You are in a position to negotiate and sell or license as you see fit. Best advice I could give you is not to sign until you speak directly with them and get what you want from the deal. It really does not matter whether you have licensed the software or are giving it away as open source code. They are looking for a reason to use a product you have rights to and it is entirely up to you how you allow that process to unfold.furthermore, you should never give up your rights to ownership, derivative work, or any other form without adequate compensation. They know this and hope that you do not. Good luck.

regards, jr