We do make it clear on our website that the service has a small monthly or yearly fee. We'll make it more evident in the add-on listing as well.

As for the access, unfortunately this is the only way to make the blocks work. We do not share, sell, or even store _any_ data from your email account. I'd encourage you to read our privacy policy (https://blocksender.io/privacy/), which explicitly states that we do not save any data from your account.