If you have the evaluation copy of the product installed, it is not mandatory to reinstall the purchased product. [Except for Vtune Performance Analyzer]. Reinstallation is required only if you want to use a different version of the product.

Replace the purchased license file to the default system directory where the product was installed.

Example License file locations:
On Windows*: \Program Files\Common Files\Intel\Licenses\
On Linux*: /opt/intel/licenses/
On Mac OS*: /Users/Shared/Library/Application Support/Intel/Licenses