If you have an app that uses Bitcoin for something, like virtual goods in a game, you need to give your users an easy way to buy the Bitcoin.
There are some limitations to the buy button right now, which Coinbase hopes to remove over time. They are:
The Buy Widget is currently limited to customers in the United States using debit cards. To enable instant buys with limited KYC, the Buy Widget supports buys up to $5 per day. Each user has also a lifetime limit of $50 after which they are asked to set up a full Coinbase account. These limitations are only temporary and we’ll be adjusting them and adding more payment methods over time to increase limits.
I think that virtual currencies, like Bitcoin
Ethereum, are a great way to create “economies” in your app. So if you want to experiment with this idea, try out the Coinbase Buy Bitcoin button. Details for developers are here.