Is the annual subscription to enter a wholesale store and purchase from it—which requires either proof of owning a retail store or paying a fixed amount—considered a discount card, given that the price is fixed for subscribers and retail store owners and does not change for cardholders?

It is impermissible to purchase an annual subscription to obtain a discount due to the presence of gharar (excessive uncertainty), muqamara (gambling), and jahalah (ignorance) regarding the extent of the discount. This is precisely what prohibited discount cards are based upon. A resolution prohibiting them was issued by the Islamic Fiqh Council of the Muslim World League, as well as a fatwa from the Permanent Committee. Sheikh Ibn Uthaymeen clarified that these transactions fall under the category of maysir (gambling) mentioned in the Almighty's saying: (O you who have believed, indeed, intoxicants, gambling, [sacrificing on] stone altars [to other than Allah], and divining arrows are but defilement from the work of Satan, so avoid it that you may succeed) because they are based on a contest: either a winner or a loser, and their ruling is prohibition.