Subscriptions are directly linked to the account you use in Apple’s App Store and/or Google’s Play Store. This means that the subscriptions are linked to your account, and not to the game itself.
Please, make sure that you have downloaded the game under the same account that you've used to buy your subscription.

The first thing to do in this case is to check if your subscription is still active. You can check this in your device's settings according to the steps below:

Android (Google) -
1. On your Android phone or tablet, open the Google Play Store.
2. Tap Menu (left upper corner) and check if you’re signed in to the correct Google Account.
3. Click on Subscriptions.
4. If you see a Bike Race subscription, it means that you're correctly subscribed.

Apple (iOS) -
1. Go to Settings > iTunes & App Store.
2. Tap your Apple ID at the top of the screen, then tap View Apple ID. You might need to sign in with your Apple ID password.
3. Scroll to Subscriptions, then tap it.
4. If you see a Bike Race subscription, it means that you're correctly subscribed.

If you can't find a Bike Race subscription it means that you are not subscribed with that Apple/Google Account.

After you verify that your subscription is active, go to the Multiplayer menu and click on the shopping cart icon to open the Shop. Scroll to the right through all the bike options until you find the button Restore. Press Restore to recover all your purchases and to validate your subscription.