To download kaspersky when you already have key you just need to create a kaspersky account and then redeem your activation code inside the account. Then download and run your program. All the steps to download kaspersky already have key is described in below section properly.
You have a kasperky activation code when you already have a kaspersky software before and you purchased the license for the same
In this case if you bought a kasperky license for the same product which is already in your computer (expired or going to expire) . i.e. if you have kaspersky total security before and you purchased the same kaspersky total securtiy again.
so in this case of the same kaspersky product you just need to change the kasperky license number in your already installed kaspersky product.
Open the old application of Kaspersky and in below right hand check for account settings and change the activate license.Finally you are done.