After you purchase the WPS Office Premium subscription you don't need to wait for any license key. You just activate it using your WPS account.
After your payment, open up one of the WPS applications (writer, presentantion or spreadsheet). You can activate WPS Office from the Sign in button on the top-right of the menu.
Click the Sign in button, the login window will pop up. Just sign in your account in the Account Center.
Signing up in the account center you should use the same email used to purchase the premium account. WPS account could be you email address, gmail, facebook, dropbox or twitter account.
To confirm subscription, after log in your account, you will find your account ID on the top-right of the menu. You can check your subscription information from the drop-down menu.
You can check and manage your Subscription information at store.wps.com.
At User Center, you can reset, edit account name and password.