You can allow subscribers to gain early access to tickets by going to SETUP > SUBSCRIPTIONS > SUBSCRIPTION SETTINGS and find the Early Access Options area.
After you check the box, you can select how far in advance the subscribers will gain access to tickets. This timeline is related to the ticket on-sale date and time that you set up in your event. So, if the public on-sale time is 8 a.m. and you allowed subscribers to gain access 1 day early, sales would open for them at 8 a.m. the day before.
You can also set a minimum annual donation threshold that must be met for subscribers to gain early access. If you don't want to enable the donation minimum then you can leave the donation amount at $0.