[Why does my.ESET only assumes 1 license is used?]

On 6/12/2021 at 11:30 PM, itman said:

If you bought two 1 PC Eset licenses, the key for each license would be different.

Sorry for my ignorance, 
Yes, I mean I buy one license for two devices 

On 6/12/2021 at 9:59 PM, peteyt said:

Have you linked myeset to both devices?

Yes, I even used the same login account name for myESET, same Windows login (Microsoft Account) too, and both computers were online at the same time.

[Why does my.ESET only assumes 1 license is used?]

Recently, I bought 2 (two) NOD32AV licenses for 1 year and plan to use them for 2 computers 
Both were stationary desktop computer (not a laptop)
One for my school work and another one is for my home.

What I don't understand is:

When I enter the license (on both computers) why does my.ESET only assumes 1 license is used?
(I'm not complaining, but if I get caught later, I don't want you to think I'm cheating/overusing my license)

Now my main question is:

Can I use 1 unused license for 1 another computer? (using share my license)

Thank you for your attention, your reply help is appreciated