X2 on the above post.
Each breed is different as is each individual bird. Health, diet, spaces they are kept in, stress levels, etc...all play a big part in how often a bird lays and how long.
I keep Black Australorps and Barred Rocks. Seems like they all have layed well into their 4th year, a few to several eggs a week, slowing greatly by their 5th year to one egg a week. One of my 6 year old Australorps still lays a couple times a month.
Hens are born with a certain amount of yolks to be laid over their lifetime. When they are out of yolks, that is it for the laying. If a hen spends every summer being broody, she will have more eggs to lay later in life. If she is a power layer, laying every day when she is young, she will run out of yolks faster.
However any very young bird of 2 years or less that has stopped laying should be a suspect for internal laying. Not always, but many times this is the case.
I keep all my birds and allow them to live out their lives well after they are done laying as I keep them for my great interest in chickens, not strictly for layers.