The "Bypass Paywalls Clean (c)" version for Firefox doesn't prompt you for new domain permissions on every update, which is convenient if you trust the developer.

https://addons.mozilla.org/en-US/firefox/addon/bypass-paywal...

Whether you choose the "(c)" version or the standard version (Firefox: https://addons.mozilla.org/en-US/firefox/addon/bypass-paywal...), Bypass Paywalls Clean is updated more regularly and supports more sites than the original Bypass Paywalls.