Win10 method for obtaining keys

A key is required for Windows system installation so that the system can be successfully installed. The same is true for the newly released Win10 system preview. So where is the key for the win10 system available?
Win10 system key acquisition method:
Click to open the win10 preview version of the download page, click to start right away. As shown below.

Click to open the join page, click on the page to join immediately, as shown below.

Enter the account number and password, click sign in, as shown below. If you do not have an account, click to register for an Outlook account.

After login, prompt the agreement, click to accept the agreement, as shown below.