Yes you can. Once you have created your ImperiHome Account you can use up to 6 different mobile devices Android and/or IOS.
For former Pro user, both your iPhone/iPad have to be configures with the same Apple account (the account that is used on the iTunes app store).
Then, install ImperiHome from the App Store, launch it, go to the 'Buy Premium' screen in the left menu, and click on the "Restore purchase" button at the very bottom of the Buy Premium screen.
You then may have to relaunch the app completely for the purchase restore to be handled.