It’s easy to upgrade from the Firebase Spark plan to the Blaze plan. Here the steps.
1. Log in to the Firebase Console. In the lower left, you will see that your project is listed on the Spark plan. Click the upgrade button.
2. Select the Blaze plan.
3. Select a billing account. Then click Continue and Purchase. You are now on the Blaze plan.
For details on how to create a billing account, please see the Google Billing instructions: