my experience is that is very very hard to actually sell "value metric" SaaS products above 500€/month because charging somethign else every month doesnt fit into most (maybe its a german thing?) companies budget calculations. they dont get "maybe 6000 maybe 12000 euros" for a year to run your software they get an exact budget. unless you are directly involved intro their payment/sales funnel and get a percentage of this i doubt this is applicable for typical B2B SaaS yearly pricings.