The current commercial release (v2017-R2) of the Analytic Solver Platform and Solver SDK work with a web licensing system in which your license is tied to the email address that you registered with.
To access and use your license with the Analytic Solver Platform Excel add-in, open Excel, go to the Solver Home tab, click Log In and log in with the credentials your registered/purchased with and your license should be automatically implemented.
To access and use your license with the Solver SDK or XLMiner SDK open the license manager program:
Click on the Start button within Windows and go to All Apps -> Frontline Systems -> License Manager
and click Log In at the bottom left (you may have to increase the screen size to see the Log In button). Log in through there with the email address that you registered/purchased with and your license purchase(s) should populate in the right hand window pane. Once this is done you should be ready to start use of the SDK.