I have a copy of Cubase LE6. Will i be able to use Cubase AI without dongle (with soft e-licencer) on my laptop, after upgrading to Cubase 7.5 (upgrade plan UG4), and transferring licence from soft e-licencer to usb dongle. It’s very important to me, because i don’t want to use dongle when playing live. Risk of damaging or losing this little expensive stick on the road, is too high. 
Not possible. Your LE6 license will be replaced by the 7.5 license, which must be on the USB-eLicenser. If you want to retain the use of LE6 on the Soft-eLicenser, you would need to buy the 7.5 license at full price.
Cubase AI can be on a soft e-licenser, but it’s a separate license. You can have your 7.5 on the dongle and AI on your laptop’s e-licenser. You won’t need LE6 anymore. I presume you obtained a copy of AI by buying Yamaha or Steinberg hardware, because that’s the only way you can get it (you can’t buy AI as it’s only bundled with hardware.)
That’s what i thought. But wanted to be sure. Because of discount, it will be cheaper for me to buy upgrade and then new LE for live use. Thanks!