I really want to know if bitcoin has an age limit
No. Bitcoin is money. Unless your government places an age limit on possessing money, there is no age limit. Does the money where you are from have an age limit? Are children not allowed to have money in your community?
so that i would know if when do i retire on bitcoin
If you want to retire on bitcoin, then you will need to have enough bitcoin to pay for all your expenses for the rest of your life. Bitcoin is just money. There is nothing magical about it. You earn it just like you earn any other money (by providing a product or service and accepting bitcoin in exchange). Just like with any other money, the amount of "stuff" you can buy with a given amount of bitcoin will change over time. With most types of money you can buy less stuff in the future with the same amount of money (this is often called "inflation". With bitcoin, you might be able to buy less stuff, or you might be able to buy more stuff. It is difficult to predict how successful this money will be in the future.
or when do i start in bitcoin
Whenever you want to.
for that i will be a member or a veteran in bitcoin
Bitcoin doesn't have members or veterans. It just has people that use it as money.
This discussion forum does give registered participants a label "such as newbie, member, legendary, etc" based on how long you have been participating and how many posts you've created. Some advertisers might be willing to pay you a bit more to advertise their service for them if they think people will pay more attention to your posts on the forum. As such, some advertisers might look at the label this website has given you when they decide how much they want to pay you for advertising. Regardless, you shouldn't waste people's time with nonsense and useless posts just so an advertiser will pay you. If you do, you won't learn much, and intelligent and educated people will mostly just ignore you.
and I would like to know that if you serve bitcoin for so long like 25
Bitcoin has only existed for about 8 years. Bitcoin is just money. You don't "serve money". You simply use it. If you have skills, you are welcome to use those skills towards making Bitcoin a better money, or towards helping others that are trying to learn about or use bitcoin.
years does the bitcoin admin will give you a reward or retirement fee?
There is no Bitcoin Admin. There is no Bitcoin Company. There is no "official" bitcoin group. There is no government in charge of bitcoin.
Bitcoin is just money.