Try before block rule

The modules uses Drupal plugin framework to make it possible for other modules to add their own plugins.

These sorts of specific use-cases are best implemented in your own custom module.

Thank's for replying @akoepke, I am just writing again to let you know that I have created a minimal module to get this feature, as you said with a new plugin (also packing a block to inform the user of the rate limiting), it's in :

https://www.drupal.org/project/paywall_rate_limit/ →

I also created a new module to implement a paywall plugin depending on the subscription of a given simplenews , in:
https://www.drupal.org/project/paywall_simplenews_subscription →

Your module helps a lot ! thank you!