I click on every grammarly ad I see but I will never use or buy their service
Why do you click on them if you're not planning to use their service?
I like to see what they offer.
It's okay to click on an ad and not use their service. You can still keep updated until they do offer someone that will make you sign up.
But when I click on it every time it ends up being too expensive, but I like to check from time to time.
I can understand your reasoning. It's okay to decide not to use a product and click on their ad. It is quite fine to see what they are offering every now and then.