Annual FATMAP Premium Members (old app)
If you have purchased the annual subscription of FATMAP Premium on the old app, you don't need to don't need to do anything and you will automatically be a member of FATMAP Explore. Your expiry date will be the same as the expiry date of your FATMAP Premium membership.
Monthly FATMAP Premium Members (old app)
If you have purchased a monthly subscription of FATMAP Premium in the old app you will have access to FATMAP Offline, giving you unlimited downloads of the map to use offline, until your subscription expires or you cancel your subscription.