[preinheimer]

I run a product that has a free tier. There's one person with ~30 accounts, each with their own unique email address (gmail).

Credit cards are a decent tool to stem the tide of people making lots of free accounts.

[wantsanagent]

Fine, then charge $1 and don't auto-convert to a subscription. That practice is what is offensive.

Or if it's just a few users don't ruin the free trial for everyone based on the actions of some bad apples. Spend some time on IP based screens etc.