Click on Menu.
Select Members or click on Notifications then New pending members.
If a member has the Trial ended tag, it means that they have finished their trial period in your network. If they wish to join your network, you can select a plan (Standard or Pro) for them.
Select the member(s) you wish to add a plan to, then click Add a plan/Add an addon and finally click on the desired item.
If the member does not wish to join, simply check the box and click Delete.