1) To get Woocommerce plugin button at first you need to give permission as admin. Go to Settings->Role & permissions->Enable woocommerce, give permission.
2) Click on Enable woocommerce, put the woocommerce plugin purchase code.
3) If your purchase code is verified, you will be able to upload woocommerce plugin file.( File must be in pdf format & file size must be within 2MB )
4) After uploading file, go to payMoney front end “Developer” page. Wocommerce plugin button will be appeared here. Customer may download the plugin file which was uploaded from admin panel.