Intergration of shopify order API in own created website

I have my own website and there are 2 type of users Merchant(saler) and Customer(purchaser)

I am showing product on my website with help of shopify by creating store, product and app

I have created store with Merchant email id

When i am showing product i am showing shopify porduct API with merchant access token

which is fine

But when customer will be place order then i need to call order api of shopify so to call shopify order api i need to pass access token in header for authentication

But customer(user) doesn’t has his own shopify store

So, for this i am using merchant’s access token for calling order api at customer end

is it correct way to do that or not ?

NOTE: customer(user) does not registered on shopify