Solution 31491: TI-Nspire™ or TI-SmartView™ Software Activation Returns an Error A18.
How do I resolve error A18 that occurs during activation of a TI-Nspire or TI-SmartView Software?
Error A18 indicates that the license number being activated has already been activated on this computer.
No additional steps are needed to resolve this issue.
If you have any additional questions or concerns regarding this error, please contact TI-Cares Customer Support.