register license - how

I have a 3 device licens and have used 2 of them for my laptops.
I also have a Samsung Galaxy Note 2 and I have the mobile security. I go to the app on my cell and click on GO PREMIUM and then I click on UPGRADE To PREMIUM. The phone then says upgrade or I can click on “ALREADY HAVE A LICENSE”. But nothing visible happens. What should I expect. How can I regeister my device? Thanks

You can’t apply license for PC to mobile device.

Is it really so? where to buy a license that has been written for the three devices, and there was no warning of mobile or clarifications that only for desktops and laptops.

Yes.

it badly veiled deception buyer

When you are buying your license it is pretty clear you are buying a 3PC license for X number of years.

See attached image, this is from avast.com Products and purchasing.