I have not sold on my Ebay account since Sep/2017 and don't intend to resume selling on this account until the end of Jan/2018.
Will I get suspended for this inactivity period?
You will not have a problem idling an account. But the major thing I would do, would be to clear up all balances and cases, if you have any. Also, you will have that lingering buyer that wants to complain. I would log in to check messages and make sure no cases go unresolved. If you miss this crucial step it could ding your metrics and be fatal to the account if the right scenario happens.