JetBrains is a cutting-edge software vendor specializing in the creation of intelligent development tools, including Toolbox App, IntelliJ IDEA, PyCharm, WebStorm, PhpStorm, ReSharper, Rider, CLion, Datalore, DataGrip, RubyMine, AppCode, GoLand, ReSharper C++, dotPeek, dotTrace, dotMemory, dotCover, YouTrack, TeamCity, Upsource, Hub, Kotlin, MPS, PyCharm Edu, IntelliJ IDEA Edu. However, most of them need license activation. You can buy through https://www.jetbrains.com/idea/buy/. 

Following a few steps, you can register these products. Test was sucessful in version 2019 series and 2020.1, on mac os, linux, windows.

1. Hosts

Add a few records to the hosts file. Be sure to add, or it may fail.

1.2.3.4         account.jetbrains.com

The hosts file location is different for different operating systems.

mac os

/private/etc/hosts

It can be opened and edited using the nano command.

$ sudo nano /private/etc/hosts

linux

/etc/hosts

windows

C:\Windows\System32\drivers\etc\hosts

2. Enter License Number

Select Help -> Register...

Select activation code.

Try these activation code below.

If the above activation code is invalid, you can try this article Permanent trial Jetbrains Product.