I'd be a lot more willing to consider a somewhat larger single payment that gets me a lifetime subscription than a monthly fee. I'm pretty sure I don't want to deal with a monthly fee, even if it's $1, it feels like having to do the buying decision over and over again every month, but I can entertain dropping a one-off $20 for a lifetime subscription. Of course that'd only net less than two years worth of posts even for the $1 monthly price point, so this might not be such a great deal for you.
I wouldn't do a lifetime subscription simply because I know that there's a very high chance I would stop or the quality would go downhill at some point. Even if people were willing to trust me and pay upfront, I would still consider such a pricing strategy extremely dishonest.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.