Yes, if (big if, see bold text below) there's at least one valid question specifically about an aspect of that service.
Of the two where it clearly didn't apply, I removed the tag. Of the other two, one is already closed. The last one is this:
Marvel Unlimited - comics aimed at young children
To me, this feels like a shopping question. It's asking for details about shopping for a service. Sure, it's a specific service, but it's still a shopping question. The answer could very well be outdated considering it's an ongoing, changing service.
It's akin to asking "Is X show available on Netflix?" which is off-topic.
So, in my opinion, this last question should probably be closed as off-topic, and then the tag removed from the closed questions as it's not really necessary. But, so long as we decide to keep that question open, the tag fits.
If tag is to stick around, I would expect a more appropriate use to be asking stuff about Marvel Unlimited related to the general Marvel fandom or the company, rather than just general "can I read X on Marvel Unlimited" questions. For example "Why did Marvel launch Marvel Unlimited?" or "Are some comics released exclusively on Marvel Unlimited (and not in print)?"