AbleCommerce Shopping Cart Software

I need to generate keys for digital products using a third party's api. Ideally I'd like to do this as soon as authorization is received from paypal through the ipn. Is there any way I can hook into that event? I thought of using the receipt page but there's no guarantee that the purchaser will come back to the cart after going to paypal.

Thanks!
Stephanie

Is this forum no longer supported? Questions used to be answered pretty quickly in the past...I guess it may be a stupid question, I just don't have time to hunt...