Yes! There's no commitment to stay on any plan and you can change each month as your needs fluctuate.

When you change to a higher plan you will be immediately upgraded and have access to the benefits of the higher tier. So if you have hit your coverage limit for the month but want to continue uploading, just upgrade for immediate access to the higher limit.

When downgrading, you will retain your current tier until your renewal date. This means you can downgrade at any time to switch your plan when you renew.

If you only need the higher tier for a single month, then just downgrade again after your upgrade goes through and you will just move to the higher plan for your current month.