Every family member account is bound to that family manager which created it.
However, you can use the same family manager account on several devices. Just install the app on all devices you want to and log in to the family manager account with email and password that you used when registering that account. If you forgot your password, tap Forgot Password? in the bottom of the screen (see What to do if I forgot my family manager account password?).
License is bound to the account, not the device, so you do not have to buy another one. License should activate automatically after you logged in, but if for some reason that did not happen, you can activate it manually (see How can I restore a license if I reinstall Dr.Web Family Security?).
If a family member sends a push notification to the manager, all devices with active internet connection will receive it.
