From where I can buy subscription?
You can purchase the subscription directly from the app itself.
If you are an android user, Click on Menu > Purchase subscription and you can choose your own plan. If you are an Iphone user, Click on More > Purchase Subscription. User can make payment through Netbanking, Credit/debit card, UPI etc directly from the app.
Once the payment is successful, you can fill out your company details and the invoice will be automatically emailed to you.