In order to register an AVG product:

1. go to http://www.avg.com/registration
2. enter the licence key
3. enter the code which you will get in return into AVG program, under options

In order to renew a licence:

1. go to http://www.avg.com/us-en/upgrade
2. enter licence key and follow the steps
3. the licence will be renewed after you complete this process