It seems there is no code to act with a second or a recurring subscription.
Example:
Sub 1 Membership 30 days
Sub 2 Membership 365 days
User 1 buys Sub 1 for 30 days;
two days before running out he sells sub 2 for 365 days.
After the last day from sub 1 the cronjob kills his additional usergroups he paid for beacuse sub 1 is finished. But there is no proof if he has bought a second membership meanwhile.
Example:
Sub 1 Membership 30 days
Sub 2 Membership 365 days
User 1 buys Sub 1 for 30 days;
two days before running out he sells sub 2 for 365 days.
After the last day from sub 1 the cronjob kills his additional usergroups he paid for beacuse sub 1 is finished. But there is no proof if he has bought a second membership meanwhile.