Your aCalendar+ license is not bound to your phone (or phone number) but to your Google account (or Amazon account if you purchased in the Amazon App Store).

In case you upgraded as IAP (in-app-purchase) you need to install the regular aCalendar app (not aCalendar+) and features will unlock automatically (you can alwaysc check the upgrade status by going to MENU - Upgrades).

For more details see About Upgrades the pages on Google Play and Amazon App Store.