If visit visa as u r saying not business or work or whatever ... then u will have right in 6 months even it mentioned in the visa one month . after ure friend finishes medical and that should be before the first month gets expired . wait for result after u can extend it in jawazat by paying 200 Qr. for every month of extention up to 6 month . if he wants to stay for the 7 months he will take air ticket of the last day of the 7th month its easy. for u to extend u will need original passport visa copy and debit or credit card. hope this helps u. good luck