A fully favorable ALJ decison usually contains a sentence like this:
The claimant's earnings record shows that the claimant has acquired sufficient quarters of coverage to remain insured through December 31, 2013.
Sometimes the successful claimant will read that sentence and think that it means that the Social Security disability benefits will terminate on December 31, 2013. But that is not what the sentence means at all.
This language in the decision simply refers to the date last insured, which is the date by which disability must be shown, to be eligible for benefits. The date has nothing to do with continuity of benefits once a claim is granted. So please do not worry if you see this language in your fully favorable ALJ decision.
Occasionally an ALJ's decision will suggest a time frame for review of disability status. Also, Social Security conducts periodic disability reviews of cases in pay status to ensure that the beneficiary remains disabled. Should Social Security determine that there is medical improvement and that disability benefits should be terminated, you have the opportunity to contest that finding.
In general, if you receive a fully favorable ALJ decision, your disability benefits will continue until you get better, or return to work at the SGA level, or reach retirement age, or die.