I dont know if it's possible to compare the presidency terms and conditions of IRI with any other country around the globe, though here in US and acc. to the twenty-second amendment of the constitution it is prohibited of being elected as president for a third term.
As it is now and for the most of the countries (democratic/non-democratic) around the globe with a government running by a president the terms are;
* Term length: Four years, renewable once.
* The President is directly/indirectly elected for a four-year term, renewable once and not permitted to run for a third term or serve for more than 8 years in the office.
However, we are talking IRI and that means anything is possible as long as gud not forbid it, though god knows shit about what's going on in IRI and therefore can not forbid it, so its fully possible for AN to have a run for a third term.