Take a second and go out to the Google Play Store or iTunes, and search for free apps. How many came up? Some number this side of a google? (Sorry, bad pun.) But the answer is a lot, right?
If you clicked through to some of the better known apps, you'll find they have a free level and one or more paid levels. Tech companies are marketing geniuses when it comes to knowing how to lock down some of their features in order to entice people to upgrade.
Associations that offer virtual memberships or entry-level membership tiers could learn quite a bit from them.