Changing between Phone platforms

Can anyone help I have been using the full app on Android and just moved to Apple can the subscriptions be swapped over?

Welcome @Andrew_Waddell
Most questions can be answered with a simple search or reading the Litchi Help Info.
Your question has been asked and answered multiple times on here.
But, here you go.

From the Litchi FAQ:

10. I purchased the app on one device, can I install it on other devices?

You can install the app on as many devices as you want as long as they use the same platform and the same “main” account (Google, Apple or Amazon) that was used for the original purchase. If you wish to use Litchi on two or more platforms you will need to purchase it on each one.