Issue: "The previous activation key has not been accepted by the license server."

I copied and pasted the updated license for DP 16 from the dashboard, then it asked me to fill in the license for the previous version, I copied the license for DP 15 again, then I was prompted for this: "The previous activation key has not been accepted by the license server.".
Any help would be appreciated!
PS. I am activating on two computers, but will not use both at the same time, is this allowed?

 

Hello, could you provide us with your license key via the private message please?

 

Could you please tell me where can I send you a private message?

 

Hello?

 

I've just sent you a pm, please check your inbox and reply.