Realistically, it depends on the price point/time interval. A week seems like a really small time span for a subscription and as a lot of people have pointed out, subscriptions are generally automated memberships.
That being said, I don’t think this idea is without merit. I feel like little ‘combo packs’ for like $5 that gave you say 100 Hero Points, 2000 ISO-8, 3 Rainbow Boosts, and 1 Heroic Token are something that would be a worthwhile investment. Scale them up as the price point increases; $10 could net you say 250 Hero Points, 5000 ISO-8, 3 Rainbow Boosts, 1 Damage Boost, and a token that would give a 3* or better. $25 could give you 750 Hero Points, 100000 ISO-8, 6 Rainbow Boosts, 3 Damage Boosts, and a 4* cover. (These are just random metrics, I’m not claiming these are necessarily worth the price point.)
If they wanted to go with an actual subscription model though, it would have to be something reasonable. I’ll use a game I used to play a lot as an example. The game was called Triple Triad Extreme (Dark Winds in earlier iterations) and we had four “Memberships”; Gold, Platinum, Diamond, and Power User. We also had two forms of currency (GP/Gold, AP/Silver) and “Tokens” (which were exchangeable for cards). The way it worked was each membership gave you; /x/ amounts of Tokens, /x/ amount of AP, /x/ amount of Gold, %/x/ increase in Gold income, %/x/ amount of EXP income. They cost $5, $10, $15, and $20 dollars respectively.
Spoiler is a break down of the rewards.

A card pack cost about 1200 Gold on average, so even with five dollars, you got at least two packs right from the get go. That felt good. Tokens could effectively get you any card in the game - and yes, you could cherry pick. 1 Token could get you any card from Level 1 to Level 7 (which were the “average” cards"), 2 Tokens could get you any Level 8 or Level 9 (“above average”), 3 Tokens could get you any Level Ten (“best”), and then 4 tokens could get you special Token-only cards that were a small cut above normal level tens (but not game breaking). So if you really wanted a card or you only needed specific cards to finish a deck, you could just give the RNG the finger and grab it or opt to get a neat SE/EC like Triforce that was a cut above the rest of the card collection. It felt not only rewarding instantly, but it felt like it was worth the money. Everything about it was notable (except AP, but that was because AP itself wasn’t notable). You noticed the increased gold and exp gains. Some of us even charted it at one point and were flabbergasted. Keeping in mine Triple Triad is a game placed on a 3x3 board. A match takes a couple minutes, so that percentile added up ridiculously fast.
Just some food for thought.