Cannot enter licence key | Internal error, please try after some time (Error code: 2)

Hi everyone,

I installed a demo version of plesk about a week ago and bought the real one a few days ago. Every time I try to enter my licence key it says " Internal error, please try after some time (Error code: 2) ". I am not great with linux so if I need to do some backend stuff to fix this issue please don't get annoyed if I don't understand .

Thanks