If you upgraded your subscription from the iOS app but you can not access your Premium or Pro features, your purchase might not have been registered with us. If you have been charged and received a receipt from iTunes Store, please try the following:
Download the latest Soundtrap app release (1.2.2 and above) from the App Store. In the Soundtrap app go to Settings->My Subscription. In the top right corner there is a dot-dot-dot menu. Tap to open it and then tap "Restore purchases". This should resend your payment information to us so that we can register that a purchase has been made. Now you should be able to access your Premium or Pro features. If not, send an email to support[at]soundtrap.com and we'll help you.