When you activate the plugin you will see one notification asking you to enter a purchase code. You can get your purchase code following this steps:
a) Log in to your codecanyon account.
b) In the top menu you will see your name. Under that menu, click “downloads”.
c) Find WP Sheet Editor in the downloads list.
d) Click on “download” and select “license code and purchase code”.
e) It will download a file containing the purchase code. Copy the code and paste it in the form in your WordPress site.