But, you do not have to have a ticket when you make your initial ADR, if that's what you're asking...
If you have resort reservations you can still make ADRs at 180 days plus 10 even if you have not yet bought park tickets.
If not staying at a WDW resort you can make ADRs at 180 days.
But, to actually eat at the restaurant you must have (pay for) park admission. And if you change plans, you need to cancel your reservation, or your cc will be charged the $10 pp cancellation fee.