IDA 7.5 replaces IDA Starter and introduces 5 editions of IDA Home. IDA Starter users with an active support license will be upgraded for free.
Corporate customer's licenses will be converted automatically to IDA Pro.
Private customers can submit here to which IDA edition they want their license to be converted to. The conversion is free of charge; future support extensions will be at the cost of the chosen edition. If you don't express any preference by submitting this form, your licenses will be upgraded to IDA Pro.
In some cases (e.g. the presence of decompilers or multiple seats), the upgrade to IDAPRO might be the only option available.