Membership+ Same Membership Levels - Monthly & Yearly Subscriptions

1) We want to only have 3 membership levels offering monthly & yearly subscriptions for each level.

We need the 3 memberships to only be set up as 1 level.

What we do not need is 1a 2a 3a subscription levels
1b 2b 3b
a= yearly b=monthly
totaling 6 subscription levels

2) How come I see the progression? What is that? In the Subscription plans
Is that just progression of level1 > level 2 > level 3?