If I have a bronze, silver or gold membership, am I going to have to renew each year (or every six months in the case of bronze/silver) in order to keep the component current and safe?
The core JEvents component is free to download.
For the cub addons you can carry on using them after your membership expires and then only renew if you need to update the code (for new features or to support changes forced on us by Joomla updates etc.) or need specific support. No need for ongoing active membership.
In the event of a high risk security fix we will release a security patch for club addons so you don't need to renew to get the fix. This hasn't been necessary in the past.