Use SilkStart's CRM (Customer Relationship Management) features to log an activity such as a Note/Email/Call/In Person Meeting on a member's profile. Include a title, date, and text body in every activity you log.
Logging an Activity: Admin Panel > 'Manage' > 'People' > Edit Member > 'Activity Log' > Log an Activity
Can I log an activity for a contact (inactive member)?
Adding the prospect to your database in SilkStart won't have an impact on how this person uses the system if they become a full member, and helps you manage both your active members and your prospects in one unified place.
The ability to log activities is indeed a useful feature in this case, and can be used for any member in the system. Note that the note logging system is currently only available on people's profiles - you can create inactive profiles for a company and your key contact, and log notes on the key contact's personal profile.
Note for Multi-Chapters:
Activities logged on a user's profile in one chapter are only visible in that chapter. For example, if you log an activity for John Smith at the parent network, chapter admins will not see these activities. If a chapter admin logs an activity for John Smith in Chapter A, the activity will only be visible in that chapter.