Below is an example.
Membership A (10 $)
Membership B (100 $)

If you subscribe Membership A for 360 days, the expiration date is 1 year.
If you change to membership B from that state, the expiration date of membership A will be taken over.

Therefore, the expiration date is calculated as A + B.


Users who notice this naturally buy a lot of A and then buy a B.

How can I automatically reset the expiration date that the user has when changing the plan?

sorry 1year is 365days.

@poppo
When upgrading from lower to higher plan, expiration date is replaced, when downgrading, expiration date is added. When same membership is purchased again, expiration is added.