Verifying Google in app purchases on the server by acknowledgementState and consumptionState only

Question

I am trying to implement in app purchase verification for Android using my own php backend server.

I have been able to get the server running and verified my service account with google apis.

I am reading this link: Verify purchases before granting entitlements

According to the link, I must compare my purchaseToken to previous purchaseTokens that were stored in my own database.

However, I see the response of the server contains an AcknowledgementState and ConsumptionState fields.

I plan to use these two fields in order to verify the purchase. On the client side(android phone app) I plan to use the following logic:

boolean isAcknowledged=false;
boolean hasBeenConsumed=false;

if(acknowledgementstate == 1){
 //means Google servers acknowledged the purchase.. so is not a fraud purchaseToken
 isAcknowledged=true; }

if(consumptionState != 0){
  //according to google api docs.. 0 = yet to be consumed purchase; 1 = consumed(it was 
  //granted already)
 hasBeenConsumed=true;
}

Now, I see no need to implement the database that stores all my previous in-app purchaseToken values! I can just do this:

if(isAcknowled && consumptionState == 0){
  //I should have a legitimate purchaseToken that has been verified by google servers and the   
  //the purchase has not been consumed!

  //I should consume the purchase right in here!  How can I use the Google Apis to consume my purchase in my backend server ????

}else{
 //something is wrong: it can be a duplicated purchaseToken or some other type of fraud!
}

Please provide any clarification or any problems that you see might arise from this implementation. Here is a sample of a test purchase that was previously consumed and acknowledged by Google servers.

my server response:

{"acknowledgementState":1,"consumptionState":1,"developerPayload":"","kind":"androidpublisher#productPurchase","obfuscatedExternalAccountId":null,"obfuscatedExternalProfileId":null,"orderId":"some # cant show","productId":null,"purchaseState":0,"purchaseTimeMillis":"1718701365611","purchaseToken":null,"purchaseType":0,"quantity":null,"regionCode":"US"}