Can one PlayStation Plus subscription be shared between multiple PSN accounts on the same machine?

I recently bought a 2nd PS4 (unit 2). I gave my old PS4 to my son (unit 1), which was my primary. On unit 1 all user has all the benefits of ps plus, multiplayer included. On unit 2, since I will be the only user on it, will have to sign in my name at all times to have my ps plus benefit. Currently I can play destiny multiplayer, download free games on ps store, etc. if another user signed in on unit 2, this would not work. Only your primary ID would work on unit 2. Makes sense?

PlayStation Plus online play limitations currently appear to be at the developer's discretion from my personal experience. Although this may change in the future. Your mileage may very over time.

Case in point: Using a PS4 with several user profiles created. Two of the accounts have PSN+ subscriptions. The others do not.

On the recent Destiny Alpha. The primary account had an Alpha key. Other accounts on the PS4 (both with and without PSN+) could boot the Alpha from their profile and play the initial game with on-line multi-player, but it appeared that some missions were locked out to PSN+ members only.

Warframe, downloaded and installed by the primary account was playable by non-PSN+ profiles with no issues.

On Resogun (when we tested it), all of the profiles could play on-line with friends, PSN+ subscription or not.

So, again, it will probably be a case by case basis but I'm going to guess that micro-transaction MMO's are going to be more liberal with access where as games with a user specific token (like an Assassin's Creed game) will only allow on-line play by the one account.