I want to renew my licence on an XP computer using this Windows 7 computer

Marios, Have a look @ this article (https://support.avg.com/SupportArticleView?urlname=How-to-renew-or-upgrade-your-AVG-license).
AVG Guru

I need instructions how to pay using this windows 7 computer for the renewal of a product on a different  XP computer. I do not like to let my credit card appear  on a less protected computer like an XP computer.

Marios, Have a look @ this article (https://support.avg.com/SupportArticleView?urlname=How-to-renew-or-upgrade-your-AVG-license).
AVG Guru