How do i get the renew license key?

I'm not sure why you seem surprised by this. Virtually all "paid" anti-virus software works this way. You buy the product for a certain price, which usually gives you use of the software and 1-year of updates (malware signature and program updates). At the end of that year, you need to pay to renew your product support for another year. The renewal is usually at a discounted price (i.e. it's less to renew than the original purchase price).