Where was the product sold from!

Please help ... this could be a life saver.

Here's the thing: I offer help on hundreds of thousands of academic questions (~ over 200,000)... each tutorial for a couple of dollars...

Somehow I should be able to tell which post id (or the question in other words) was the payment made from - to know which question to solve ... and email to my student. It doesnt make sense for me to put a product code in each and every post.

Just something to edit in the post.php generic post template such that the cart appears in every post.

So - I'm simply looking for a way to know that a transaction was conducted from which post/page, so I can figure out the question the student needs help on.

Maybe this will help many in the future, if someone could help!

In anticipation THANKS a tonne ... and I need this like medicine, PLEASEEE help!!!