The licence suspension comes after a 16-year-old test purchaser was able to buy a two-litre bottle of cider through the self-service checkout without being asked for identification, despite the transaction being authorised by a member of staff.
The store, which claims to operate a Challenge 25 policy, will also have to double the number of personal licence-holders who man self-service checkouts when the suspension is lifted.
The member of staff responsible for authorising the purchase is also being re-trained. At the time of the incident he had been busy supervising eight self-service tills.
Local independent retailers and consumer groups have criticised Glasgow Licensing Board for not imposing a suspension on the entire store, rather than on just the self-service tills.
The same board had previously imposed two-week suspensions on small retailers for failing their first test purchases.