You can easily change your membership level directly in the app.

If you upgrade to a higher level than your current one, the change takes effect immediately. This means a new 30-day period starts right away, and the amount for the days you have already paid for is deducted from the new monthly cost.

If you downgrade to a lower level than your current one, the change takes effect only after your current billing period ends. Your next payment will then be based on the new, lower level.