Minion Masters Gift

To exploit Steam trading cards, the devs gave away activatable copies of the game like crazy, before actually making the game properly free (something which they'd publically announced long before that they intended to eventually do).

The Minion Masters gifts don't grant premium; Rather, premium versions of the game were never offered in any sort of [bundled, free, or gift-copy-creating] promotion, so you can be assured that this is for the base game alone.

Also, good luck managing to get rid of any copies you may have. Plenty of us out here with 3 or more copies (as I recall, users received one copy to inventory for every other game by the developer owned, plus two for owning Minion Masters itself) who've been trying to get rid of their copies with no luck for a long time now. It doesn't help that, on top of the gift copies, the developer offered countless CD key drops for the game (though those at least have since been expired).

I know I have never bought premium (and I have it)

You own this? If you ever purchased the base game before it went free (or at least, before it did so through a method not involving gift copies and CD key drops), you were actually paying for the [free] base game + premium upgrade DLC, so perhaps that'd explain why you own the upgrade?

If you just want to get rid of them gift them to me