rfc: Pricing strategy changes

[Blaumaus]

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Describe the solution you'd like?

Right now we charge only per events.

Introduce plans as well, like:
Essentials / Pro / [Enterprise - contact us]

And the Pro plan will have access to some features that are more resource hungry (like A/B tests, AI chat, etc.)

Additional context

No response

How important is this feature to you?

1 (Not too important)