Can anyone help me to authorize my key for single-use?
I have installed a fresh window and all software has gone due without un-authorization.
Now, I am unable to activate my key on a fresh installed software Arcmap.
How can I fix it?
It sounds like you reinstalled your Windows operating system, but you didn't de-authorize your ArcGIS licenses first. If that is the case, you need to contact Esri and speak with someone about what options are available to re-license your software.