Problems with the device.
If you obtained a GOLD subscription from an Android device, it is very probably that you might have problems to log in from an IOS device and vice versa. Try to log in from a similar device to the one that you used to buy the subscription.
If you have the same SWISH account open in several devices at the same time, this might cause login problems. Try to log in in just one device at the same time.
Problems with the mail
Sometimes the account can be linked to several mail accounts. If you have paid for one GOLD subscription, check in “My subscription” from the “Profile” screen to see which is the account status. If the status is “FAN”, try the following: