@Donald-and-Frank0 The offer was a free pass to a paid experience, but there was no obligation attached if it wasn't your cup of tea.
If you're frequently active in these forums, the moderators may occasionally invite you to participate in an online group activity or focus group for research purposes, and sometimes they just offer something as a gift because people might enjoy it. I see no harm in it personally, but if you'd rather not receive invitations from the Admin, you can ask them not to contact you and I have no doubt they'd respect your wishes.