• Validity of Invoice without my name as buyer ?

I do IT job from which I earn taxable income and file ITR.

Recently, I started doing a side business. I sell retail subscriptions of online VPN services. 
What I do is , for example, I buy 1 Subscription of VPN at 4000 INR as a retail customer and then I sell it to 4 students at 1250 INR each, so total I get is 5000 INR. This means I make profit of 1000 INR i.e 20% profit.

My total turnover is much less than 20 lakhs so I am not concerned about GST. 

My Concern is mainly about paying income tax. So if I receive 1,00,000 in my bank account then my actual profit is only 20,000. Rest 80,000 I spend in purchasing VPN from the online vendor. 
=> BUT My PROBLEM is that in the invoice that vendor website generates my Name is not there. Vendor's GST , name and all details are present But my name is not added in Invoice. Vendor will not add my name as its a big company and only sells B2C and not B2B. 

So what do I do for tax compliance - 
#1) Do I have to pay tax on the total 1 lakh that I received in my account ? 
#2) Can I pay tax on only 20,000 profit ? But will IT dept accept the invoices without my name on it ? I have Bank Transactions that prove the validity of the invoices showing payments to Vendor.