FetchApp allows you to specify license keys / serial numbers for each product. When an order is placed, FetchApp automatically assigns the next unused one and emails it to the shopper. This is handy if you sell software or products that have unlock codes.
To get started, prepare a list of your keys separated by commas or one per line.
1) Go to the Product in FetchApp
2) Click on "Edit License Keys"
3) Click on "Add License Keys"
4) Copy and Paste in your keys and click Add License Keys
That's it! FetchApp will automatically choose an unused key the next time an order comes in.
NOTE: While FetchApp does handle the delivery of the file and the license key, we do not secure the file itself, and you may need to build custom functionality to do so. FetchApp always delivers the same file on each order (we do not generate locked files that are opened by the key we deliver). Please keep this in mind as you plan around this functionality.