The things I would be ok paying a subscription for:

• Rotating free Games that I get to keep. Like epic but only for subscribers. The game should be mine even after I quit the subscription.
• Extra insights in preservation, or goodies
• voting rights on what games should be free next month for the sunscribers.
• discounted price on games.

Things that I feel it shouldnot be locked behind subscription and paywall:

• tool for backing up offline installers
• ability to install previous versions of game
• and definitely not voting rights on games to bring into the preservation program.

If the tooks for backing up offline installers or ability to install previous versions of game are paywalled, that is going to invite more reasons for piracy.