Please log out of your account and log back in - you should have the premium subscription purchased with all features enabled.
Make sure to use the premium account credentials (username OR email address and password).
Note that username IS case sensitive.
If logging out and back in does not help and the purchase was made via iTunes or Google Play store please try to "kill" the app and open it again and/or reboot your device.
The content can be unlocked by playing missions one by one or by taking Skill Tests to skip content in syllabus.