This is more advanced: We want to sell activation keys for digital products. We know that in Craft a variant has a stock. So every single item "in" the stock needs a unique activation key. When we sell one item of the stock we sell a activation key. Of course, an activation key can only be sold once. For each product we will have a limited number of activation keys, so this will be reflected by the stock number itself.
We know that this feature requires some customization. Question is: is this achievable in an easy or hard way via Craft Commerce? How would an elegant approach look like?