Hi, I’m Tobe, the developer of Regios Automatic Discounts.
With Shopify’s built-in discount codes, you can create discounts that:
- Apply for 1 year (set the end date 1 year from now)
- Give 100% off select items
- Is only usable once per customer.
If you do so, then you’re right - you would have to create a new discount code once per month, and send it to your specific customers who won your giveaway.
Each new discount code would probably need to have an end date 1 month into the future, and have a once-per-customer usage limit.
As of the time of this writing, automatic apps can’t limit usage to once per customer. Otherwise, they would have been a good option.
I’ll keep you updated if I ever add the functionality you’re looking to your app.