Indigo includes a 'Web Update' feature in the 'Help' menu that will automatically check online to see if there are any updates available. If an update is available it can download and install the update.
Additional information on the Web Update feature is listed in this help topic:
>> Web Update
Another method is to manually check the version of Indigo you have installed by viewing the 'Help -> About' dialog and comparing it to the latest available download on our website. You can use the link below to see and download the latest available version of Indigo. You can download and install a newer version directly on top of an existing installed and licensed copy of Indigo.