You are eligible for a $25 discount from any of the monthly Bitrise Pro plans forever, if you are a Bitrise step contributor. For example, in case of the plan with 1 concurrency, which means infinite builds, team members and 45 minutes per build time, it's 50% off every month. Check out the pricing page to see what you can get.
For the details about how you can become a Bitrise Contributor and get the Contributor Discount, please see: discuss.bitrise.io/t/bitrise-contributors/167