Extended License are needed when the usage goes beyond the Standard Royalty Free license. If you need those special additional rights, you will need to purchase an additional license to the standard one. You can do at the moment if you know that you will need that extended use or also later in the case in the future you would need the rights the extended usage grants.
The extended license is needed in these situations:
Unlimited reproduction/print run
Multiple users can use the file
Create any products for resale (including print on demand products and electronic templates)
1- You know that you will need am extended license from the start. You purchase in the cart the Standard license and add the extended license.
2- You have purchased a RF Standad license in the past and now you need that the image can be used by other people of the team or firm, then you can come again to the site and purchase that extended license.