Useful information and thanks again Guitar God, ardsong and Henri for the info. My situation is similar to the first two of you, like I said I'll probably receive about half of my AOW in the future (without a pension though, we have our own business).
And Henri is correct as well; I can't pay in myself anymore; somewhere in the past I received letters (through a Dutch address) that I would get a hefty fine if I wouldn't insure myself for health insurance in NL, and deurwaarder threats since I was an NL citizen.
Through a bunch of letters and copies, I proved that I was insured already with the Thai SSO (I have a work permit) and this was waved away. Years later I thought to check if I could pay in again, but I was already much too late, and cut off, and couldn't contribute anymore. I called a friend who owns an Assurantiekantoor ( Insurance broker) and he stated the same and said it would be more useful to forget insurance and try some own saving...
I didn't bother too much, because you never know what it will be in 12 years from now. For 'expats' certain countries, the AOW will be cut anyway, for example Indonesia and Vietnam (no treaty) interesting to google sometimes.