I purchased a year subscription and want to add the app on all my devices. I can’t find the sign in on my app. It’s asking me to sign up for premium (which I already have)

There is no important information here to be able to help you. If you’re talking about a 3rd party app with a 3rd party subscription you’re going to have to get in touch with the developer of the app to find out how you can get the subscription active on your iPad as well. If there is no way to sign in, you can get in touch with them to find out how you can.

Apple does not have an ability to assist with 3rd party apps as they have no control over them. If it is an Apple app or program, they usually are connected to your AppleID and when the device is signed in, it’s got the access it needs to know that you have the “premium” subscription. Apple doesn’t typically use “premium” in their subscriptions so I would imagine that it is 3rd party and as stated above you should get in touch with the developer on how to get signed in on other devices.

You’re going to have to give us more information:

Which app is this?

Was the subscription purchased using the same Apple ID as is being used with the app?

Have you Downloaded the app & chosen to restore purchase?