Requires an account and a "recent" fuel-lock. To lock-in a fuel price you need money in the 7-Eleven app account. Funds can be added by credit card or transferring from a physical gift card bought in store.
This has been a long running deal since at least August 2017 and I grab a free coffee every month.
One coffee per account per device.
I haven’t crunched the numbers but I feel like I get more than one free coffee per month with my ‘keep fuel locking’ promos