Option #1

Event Settings - set Use Member Pricing to YES

A person would need to log into their portal account.  If they are a member then they will see the member price for that level on the event page.

Option #2

Event Setup - in a level set Member Only Level to YES

On the event page, a person will need to enter their email address.  If that email has an Active membership then they will be able to purchase that level (Qty field is enabled).

The General Admission ticket requires that the membership already be purchased/active, whereas the Member Only ticket (Option #2) would allow a person to purchase or renew the membership.

Once the Event Settings are changed (Option #1) and the step saved, a new Member Pricing step will be shown.

On the Member Pricing step, select the Membership Page, then edit the Event Level(s) you wish to set the member price for.