Select how you want to register IntelliJ IDEA or a plugin that requires a license: Select Help | Register from the main menu or click Help | Manage License on the Welcome screen to open the Licenses dialog. You cannot upgrade to IntelliJ IDEA Ultimate: download and install it separately as described in Install IntelliJ IDEA. IntelliJ IDEA Community Edition and IntelliJ IDEA Edu are free and can be used without any license. A new trial period will be available for the next released version of IntelliJ IDEA Ultimate. Upon the expiration of the trial version, you need to buy and register a license to continue using IntelliJ IDEA Ultimate. Log in to your JetBrains Account on the website and click the Start Trial button in the Licenses dialog to start your trial period. You will be redirected to the JetBrains Account website. In the Licenses dialog that opens when you start IntelliJ IDEA, select the Start trial option and click Log in to JetBrains Account. If you use two-factor authentication for your JetBrains Account, you can specify the generated app password instead of the primary JetBrains Account password. IntelliJ IDEA will automatically log you into your JetBrains Account if you're using ToolBox to install JetBrains products and already logged in there.
After installing the IDE, log in to your JetBrains Account to start using the IntelliJ IDEA's trial version. You can evaluate IntelliJ IDEA Ultimate for up to 30 days.