Unzip its contents in the location of your choice (e.g.: C:\Program Files\TIBCO\Jaspersoft Studio Professional-7.9.0\features\jdk8u412-b08-jre)
Edit the Jaspersoft Studio Professional.ini file from the Jaspersoft Studio installation folder to point to the new JRE. If you used the same path as in Step 2: -vm features/jdk8u412-b08-jre/bin
or
-vm C:\Program Files\TIBCO\Jaspersoft Studio Professional-7.9.0\features\jdk8u412-b08-jre\bin