Can I use my VIP All Access with multiple devices (phone, tablet, etc)?

Yes, as long you are using the same iTunes account, using Apple devices. 

If you are using a different Apple device, please check to make sure you are already logged in with the same iTunes account that has Active Subscription with Color Therapy. 

Don’t forget that you can always tap the "RESTORE" button if you’re already a VIP but the device has not recognized you as a VIP.