Activation disappearing every couple weeks

I purchased a 2-site license of Team Member – Team with Slider with lifetime support back in October 2021. I activated the plugin on my main site (21wilberforce.org) and the plugin works for a few weeks and then reverts back to the free version, so people can no longer see the team section on my site (https://21wilberforce.org/who-we-are/). Instead we see “This template is only available on the pro version” error message. I keep putting in the activation code and each time it works for a week or so and then disappears. What is the problem?

Do I need to whitelist an IP address or is there some other issue?

The page I need help with: [log in to see the link]