You do not need to install anything if you use the cloud based iHelpdesk service. However, if you prefer installing iHelpdesk server on your own machine, you can download the following:

Windows Installer
Linux Installer  (instructions)
(Version 3.0, build 1712)

After installation, you can try the free edition, which only allows one staff (staff includes admins and agents). If you need more staff, you can purchase the following professional edition. All editions allow unlimited number of end users.

Pricing for On-Premise Edition

iHelpdesk 10-staff Edition Perpetual License - $995.00
iHelpdesk 20-staff Edition Perpetual License - $1,595.00
iHelpdesk Annual Maintenance and Support Service - $395.00
Please contact us if you need other configurations.