I was setting up the free trial granted when someone purchases a subscription from my app, when I wondered how can I prevent someone from getting a new free trial by just creating a new gmail address? Did google think about that? How can I avoid being stolen?
I did not find anything in the official documentation.
Gmail addresses are by far the most commonly used addresses to sign up for another free trial [source: Upollo internal data]. Google, as far as I know, allows 4 email addresses per phone number over some period of time. I believe this is a recent change since this question was asked.
There are a few signals you can use to detect people signing up for another trial:
It is fairly trivial for a user to change email and change IP. Asking for phone number or additional permissions is likely to hurt your conversion rate, so it is good to use as a way of validating once you suspect someone of attempting to get another free trial.
You can use those signals yourself to detect repeated trials or you can try a tool like Upollo.ai which does this for you.