"License to Live"
You can "apply" for a "License to Live" and it grants you, government-supported, up to an extra 100 years of healthy life extension, which includes government supported vasectomy or sterilization. Only people who have had no more than 2 kids are eligible to receive such a license. People who have only had o or 1 child can get up to 150 years of govt-supported life extension.
If you become unhealthy (heart disease, cirrhosis, cancer, etc) then you are only allowed to continue receiving treatments on the public dime if they are reversing your disease. If not, then you'r left to foot the bill if you wish.
Buying your own life extension still requires the same basic child count and sterilization policy.
When the public policy runs out, you can buy your own.
People who want to have more kids can opt out and reverse their sterilization but will forfeit any legal means of life extension afterward.