Discount Code for an App with One Time Purchase

[sumanthjois1996]

I recently launched a Shopify app with a one time purchase fee of $99.

I have over 50 existing customers who used to use this web version of the app, I would like to give access to the shopify app to these customers for free.

Is there way I can give them a discount code or something? I don't see anyway to create a discount code for the app in the partner's dashboard.