Memberships
To create a new membership, go to the Commerce section of the Admin toolbar and go to Products. Click the +Add button and then select the category type Membership.
Name and price your membership and set any additional options you would like. Existing memberships are offered to visitors at checkout. If you offer any memberships, you have the option of requiring memberships for any events that you run.
Membership Tiers
You can require a specific Membership Tier for an event. Admins can also create different Price Points for various Membership Tiers.
To create Membership Tiers, either edit your organization's current membership product or create a new membership product. You will see an option to add Membership Tiers.
Once you've added Membership Tiers to your membership, you will see those Tiers as event requirement options (e.g. only Bronze level members may participate in this event).
Alternatively (and perhaps more commonly), you can assign a Price Point to a specific Membership Tier. The "With Membership Tier" box will appear once you've selected a Membership. For example, an admin could make an event free for Gold members and half-price for Silver members - all other registrants would be charged the full price.
Note that you will likely want to create separate Membership products for each Membership Tier.