First you need to download adobe illustrator and install,
Then all you have to do, to extend your trial period, is change number in TrialKey element in application.xml. This file is located in C:\Program Files\Adobe\Adobe Illustrator CC 2018\Support Files\Contents\Windows\AMT. You can go this path in windows explorer and you can see one application.xml file.
Then you have to open the file and edit it.
Now find the TrialSerialNumber Data key:
And change the last 4 digits to some other digits
Next save the file and close.
Then Open adobe illustrator adnd use it. Enjoy.
Comment in below if you need some other technical information