How do I activate?

I feel like a real dummy here I downloaded Avast Pro and got my license. How do I get activation/password?
Right now I’m running the demo.

Thank you,
bc1328

how to insert license

https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=1084

Thanks,

bc1328