Identify registration as the blocked step
Record whether the message concerns registering a new device, starting a stream or signing into an account. RTS Planeta’s device-management answer addresses the registered-device maximum. It separately discusses simultaneous playback, so a registration error should not automatically be interpreted as a temporary conflict with someone watching elsewhere.
Keep the exact message and the device you intended to add. Closing a player or deleting an application may change what is running locally without establishing that the service has removed that device’s registration. The relevant evidence is the registered-device list in the account rather than the number of application icons visible in a household.
Review the list through the web profile
Use the official site in a browser and open the account profile identified by the FAQ in the top-right area. The broadcaster says that registered devices are managed there and that the app does not offer this option. Use the same account as the device that encountered the limit.
Identify an entry carefully before any removal. A familiar television may appear under a technical model or another household member may still rely on it. Write down which device is obsolete and why it can be removed. An unrecognised label should be investigated rather than chosen simply because it appears first in the list.
Account for the stated monthly restriction
RTS Planeta states that one device can be logged off once a month. Treat the current confirmation or limit message as part of the decision before removing anything; do not assume repeated swaps are available while trying multiple replacement receivers. The FAQ does not specify a day-by-day reset calculation in this answer.
After an intended change, distinguish a list entry disappearing from a new device successfully registering and playing the selected programme. If the account remains blocked, preserve the stage and exact message for support. This keeps a limited account-management action deliberate and avoids repeating installations or removals that do not address the actual registration state.