You can use the Application Signing Services for Ovi Store to get your application Express Signed for free by Nokia. Make sure to use the application UID that you receive from Ovi Publisher Support.
The Publish Qt Symbian Applications to Ovi Store wizard allows you to check that your application can be published on Ovi Store. It checks that the application UID, vendor name, and the capabilities used meet the Ovi Publishing criteria.
If you use Symbian Signed UIDs or the application uses functions that require advanced capabilities, you must use the standard Symbian Signed process to have the application Symbian Signed (using the Certified Signed path or the manufacturer-specific channel). For more information, see Deploying Applications to Symbian Devices.
To use the publishing wizard:

Note: You cannot use this .sis file for testing.
Note: After you change the application UID, you must use the developer certificate-key pair that you receive from Ovi Publisher Support for testing the application on devices. The following error message is displayed on the device if you use UIDs from the trusted range (0x2xxxxxxx) in a self-signed application: Unable to install a trusted application from a trusted supplier. For more information, see UID.
If you try to use more capabilites than the certificate permits, the following error message is displayed on the device: Requested application access not granted. For example, if you try to install a self-signed application that uses a system capability.