will i loose my license while reinstall windows 10

No, provided it same PC, it will be fine... follow this guide: http://www.tenforums.com/tutorials/1950-windows-10-clean-install.html

when you reach the screen asking for licence, click "I don't have a key" and win 10 will continue to install and reactivate once finished. Your licence is stored on a microsoft server and when Win 10 checks your machine code, it will see its okay to reactivate and fix it for you.
 
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