The next stage of the licensing process is to convert the heads of agreement into a full legal agreement.
This will be such a complex and lengthy document that responsibility for it must be left to your legal representatives. Only they can ensure that the final agreement is consistent with the heads of agreement.
Do not regard the full agreement as an opportunity to renegotiate! We can only repeat once again that the purpose of negotiation is not to win but to reach agreement. Some of the clauses may not be as advantageous as you wanted, but any attempt to alter what has been agreed (other than errors identified by your legal representative) is more likely to ruin the agreement than improve it.
Then one day, at long last, you have your licensing agreement. Congratulations!
But this is not the end of your involvement. You and your legal representatives must continuously monitor the way the licensing agreement operates. You need to ensure that you receive your royalty payments and that the licensee is making a good job of selling your invention.
You need to watch what competitors are doing, as some may be tempted to infringe your IPR. Others may improve their products, requiring you to improve yours.
You may also want to explore other ways of using your IPR to generate other licensing opportunities - perhaps in collaboration with your first licensee, or perhaps as an entirely independent business activity.
One way or another, your work as the owner of valuable IPR will not be over. But successful inventors rarely complain about that!