Please log out of your account and log back in - you should have access to the premium subscription purchased with all features enabled.
In case you have more than one Yousician account, please check to make sure you are logging in with your 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.
If these tips do not help in resolving your issue, please get in touch with Support by clicking on the “Contact support” link located at the bottom of the article.