One native speaker said that it is a mistake to use the indefinite article in the phrase "You can cancel a subscription anytime". I want to ask native speakers if it's true, and if yes — what rule states this?
- "You can cancel subscription anytime" — not a mistake, but could be better
- "You can cancel a subscription anytime" — incorrect!
- "You can cancel the subscription anytime" — this one is ok
- "You can cancel your subscription anytime" — ok as well
- "Subscription can be canceled at any time" — the best option
So, my questions are why #1 is correct (zero article?) and why #2 was considered as a wrong variant.