The way to proceed it to be decisive in asking for what you want in exchange for the IP and work you've put in. Time for negotiation is over. Based on your past

The way to proceed it to be decisive in asking for what you want in exchange for the IP and work you've put in. Time for negotiation is over. Based on your past conversations, ask for what you think was agreed upon or what would have been fair at the time. If you can reference emails, texts, or other discussions, do it. Put it in writing, send certified mail, etc. It should be clear that 1) your work is done 2) payment or any consideration is for past works and the company will then own it 3) put a deadline for them meet your request. You should make it clear that you will exercise legal options. You may even want to get a lawyer to draft this up and deliver it to them, so it's official and carries more weight. This is a low aggression way to get what you want. Yet somewhat official and displays you are serious about getting compensated for the past work. Done right, there should be no bad blood from this. If they ignore it, and you go the legal route; the relationships/friendships will have to be sacrificed.