If you receive this error means that you have exhausted registered devices for myAVSAlarm app.
The subscription fact allows the use of the application on a limited number of devices depending on the options that you have purchased.
If you neet to add a device it will be enough to buy an additional option to your subscription.
If you intend to replace a device already exists and is no longer used simply refer to the following FAQ:
Remove Devices from myAVSAlarm