Hello Victor,
As per our record you have purchased the licenses for AVG PC TuneUp and AVG Antivirus program. For your information, there is no free version for AVG Internet Security. Only there is trial and paid version for AVG Internet Security. I guess you have already tried the trial version and it would have got expired and ask you to downgrade to free version.
Please try downloading AVG PC TuneUp using this link: http://download.avg.com/filedir/inst/avg_tuh_stf_all_2015_638.exe and run the file as administrator. When you run this file and you get options as "UNINSTALL" then it means that the AVG PC TuneUp is already installed on your PC. Please go to control panel and in the programs list check whether you have AVG PC TuneUp listed there. Please do let us know the status of this. Thank you.