First, what is disability? There are two kinds of disability through the Social Security Administration, Supplemental Security Income and Social Security Disability Insurance. The latter is based on the taxes you have paid into the system while you worked, and as such it has an end date. Just like any other insurance policy you may have, when you stop paying your premiums, you stop being insured. Social Security Disability Insurance does not stop the day you stop working, but gives you a five year grace period from when you stop working full time. This can change if you did not earn enough for four full quarters of coverage every year for the 10 prior years, but most people have around five years from the time they stop working before the date last insured expires.
So what does this mean? Well, it just means you have to prove you were disabled prior to the date last insured. You will continue to receive payments after that date if you are found disabled, but you must have the medical records to prove you were disabled prior to that date.