According to the version, you may get free trial for 30 to 90 days. Serial key is also required for installation for Adobe products. If license key is not given, contact Adobe. If you forgot Adobe CS5/C6 serial number, don't worry, this article gives you three ways to help you find Adobe CS key.The key is printed on the product package for those who bought the physical product. But there is no need to check the documents which came with the product or contact Adobe for this. This way, a serial number is required to check the registration status. Now you may want to upgrade your existing Photoshop to latest version but you don't know if program is registered with Adobe. Adobe Photoshop is used widely to create, or edit or change graphics, photos and various design elements.