That tells me how much attention I need pay to any further submissions from you.
Do we need "need to pay" in the sentence instead of "need pay"?
I reckon so.
Is, from a different point of view, "need pay" the present subjunctive as well?
(A deliberative one?)
It could be argued that 'need' in 'I doubt if he need pay' is subjunctive, though there is little point in so doing - modal verbs do not have a distinctively subjunctive form.
If a person, using the non-modal 'need' were to say, 'I doubt if he need to come,' then it would be a present subjunctive form.