To change your subscription plan, you just need to purchase at least 1 month of the desired subscription.

The remaining days in the previous plan will not be lost, but will be automatically converted into a new subscription.

For example:

1. You have 12 days left on BEGINNER subscription, and you decide to upgrade to EDGE. After purchasing one month of EDGE, you will have 34 days EDGE on your account (31 days from the purchase + 3 days as recalculation of 12 days BEGINNER)
2. You have 20 days left on HYPER for asian rooms and you want to downgrade it to STANDARD version. You just buy 1 month of STANDARD, and 71 days of this subscription will be active on your account (31 days from the purchase + 40 days as recalculation of 20 days HYPER)