How open screen with serial number input?

Hi,
I have opened Unity in Personal mode but I have Pro serial number and now do not know how back to this start screen where I can put this serial number.
Is some magic button for take me back to this start screen?
Now after start Unity still i have this personal mode and can not back to Pro.

Thanx
Arnold

Yes. There is a magic button for it. I can never find it via google.

Found it. Its under Help->Manage License.

Because the help menu is exactly where you would look to put in a serial number.