Welcome to the community and thanks for your post. I'm really sorry that it has taken so long to get back you.
If you have cleared your cache and cookies, the app wouldn't be able to recognise the devices and would ask you to register every time you used it after clearing your cookies. You can find more information here about this here
If you haven't been able to get this resolved since you posted, please let me know and we can get this looked into further for you and reset your device list.