I found one critical issue in this plugin . let me explain.
Let's say we have two memberships with Trial Subscription for 10 day
membership A and membership B.
now user choose a membership A on 10th may with a Trail Period.
so his Trial Subscription will expire on date after 10 days it means 20th may.
and now after the 2 days user updates his membership A to Membership B on 12th may so now user Trial Subscription expire date is showing 22th may and it's wrong actually it should be still 20th May. So, when user update his membership the Trial Subscription expire date is get incresed. I'm not sure if this is intentional or this is bug.