First of all, you're not able to use your membership across platforms using a membership purchased in Google Play or the Apple App Store. Platform-specific policies stop us from having that option available.
However, we do offer a membership on our websites that gives you access to both Magnus Trainer and Tactics Frenzy memberships across iOS, Android, and some web features from both apps.
Visit www.playmagnus.com/membership for more info.
If you're trying to access your Membership on another device on the same platform. For instance trying to access membership purchased on an iPhone, on your iPad. Then ensure you're using the same App Store account as the purchase was made on both devices. The same goes for Google Play on Android. You'll also have to restore purchases in some cases. More info about restoring purchase here: https://playmagnus.zendesk.com/knowledge/articles/360013169434/en-us?brand_id=360001571273