Whenever you purchase a product via the Themeforest marketplace, they will provide you with a purchase code for each item purchased. The purchase code is used to validate the software's use so that you can access theme support once you have registered your theme and for free updates. 

Follow those steps to download Your Purchase Code:

1. Log into your Envato Market account.

2. Hover the mouse over your username at the top of the screen.

3. Click ‘Downloads’ from the drop-down menu.`

4. Click ‘License certificate & purchase code’ (available as PDF or text file).

Here is an example of a PDF License certificate and purchase code: