In case if you see Activation Key is not valid message, then please copy your complete activation key with the dot(.) in the end. This will resolve the problem.
According to KNET, Burgan, CBK and other payment providers, you are required to host your website on Live/Production server so their staff can make some test transactions to verify your website. Once they verify your website they will Approve it and send you new credentials to accept real payments which you need to setup in extension configuration.