The failure to restore purchases could be due to one of the following reasons.
The solution will vary depending on the cause.

There is no subscription to restore
Another active subscription is already linked to your Pastela account
The subscription linked to your Apple Account is linked to a different Pastela account
Other issues

There is no subscription to restore

You won't be able to restore purchases if there’s no valid Pastela Plus subscription linked to the Apple Account you’re using.
Open your settings app and check that you’re signed in with the Apple Account used during the original purchase.

If you’re using the wrong Apple Account, sign out and log in with the correct one.

If you don't have an active Pastela Plus subscription, please complete the subscription process first.
For more details, see below.
Where can I sign up for Pastela Plus?

Another active subscription is already linked to your Pastela account

Each Pastela account can only be linked to one Pastela Plus subscription.
If the Pastela account you're currently using already has an active subscription, you cannot restore another subscription to the same account.

To link a different subscription, cancel the existing one first and then restore your desired subscription.
For more details, see below.
Where can I unsubscribe from Pastela Plus?

The subscription linked to your Apple Account is linked to a different Pastela account

Pastela Plus subscriptions can only be linked to one Pastela account.
Log out of the Pastela account you're currently using and log in with the one linked to the plan purchased through the Apple Account currently signed in on your device.

The Pastela account linked to a subscription cannot be changed.
For more details, see below.
Can I use Pastela Plus with a different Pastela account?

Other issues

If you're experiencing the following issues, please try again after a short while.

• Your purchases were restored, but the plan information is taking time to update on your account.
• No network connection or unstable internet environment.