Update:
I tested it with sandbox user but it seems app store won't introductory offer to those users. Here is what I did:
Create new sand box user with 3 min expiration
Subscribe to IAP product which doesn't have any offer at this point
Renew several period, 15 min or so, unsubscribe from product
Create introductory offer with first free month
Wait about 10 min
At this point the user has both is_trial_period and is_in_intro_offer_period are false
Subscribe then device shows regular price in system confirmation popup, no introductory offer
So I wonder it is either 1)Apple has some logic to prevent quick subscribe/unsubscribe manner or 2)this test is not enough time to reproduce lapsed period.
Could anyone enlighten me please?