After receiving your license file, you just need to double-click to open it and your license will be inserted into your program automatically.
Alternatively, save the license file on your computer, open the Avast Premier, Avast Internet Security or Avast Pro Antivirus interface, from the main menu select 'Settings', then 'Subscription' and click 'Insert license file'. A dialog window will open where you can browse your computer to locate your license file. Once you have located it, double click on it and it will be automatically inserted into the program.
Avast Premier, Avast Internet Security or Avast Pro Antivirus can now continue to be used for 12, 24, or 36 months, depending on the purchased license, and you will continue to receive automatic updates to both the program and your virus definitions. At the end of that time, it will be necessary simply to purchase and insert a new license key.
For detailed step-by-step instructions please read the following articles:
Inserting the license file into Avast Premier
Submit a request to resend the license to the e-mail address provided when Avast was purchased and try to insert this license into the program.
If the license insertion fails, uninstall Avast using the Avast Uninstall Utility and restart your computer.
Download and install the appropriate product version of Avast related to the purchased license. Once again try to insert the license into the Avast .