JetBrains recently released PhpStorm 8 but I could not find any information on how to upgrade. I'm currently using PhpStorm 7.
The EAP versions explicitly mentiones that a new folder should be used:
This build includes a 30-day time-limited license. There is no patch updates available.
Remember to install .zip & .tar.gz versions into completely empty folder. Do not just unpack over previous version!
Please note that 8.0 builds use separate settings folder so either automatic or manual import of settings may be required. 3rd party plugins may or may not be compatible with 134.x builds – please ping plugin authors in case of any problems. We gladly offer them our support.
Source: http://blog.jetbrains.com/phpstorm/2014/03/phpstorm-8-early-access-program-started/
I don't know if this also applies to the final version? Is there any public info on how to upgrade?