Access setup
How do I prevent invite link leaks in a paid Telegram group?
Give each buyer their own invite link that holds one member at a time, and revoke it when their access ends. Telegram's member limit counts the people in the chat through a link at the same time, so a one-member link stops a second person while the buyer is inside, and a revoked link stops everyone. Keep the group private and never share one permanent link for paid access.
Short answer
Give each buyer their own invite link that holds one member at a time, and revoke it when their access ends. Telegram's member limit counts the people in the chat through a link at the same time, so a one-member link stops a second person while the buyer is inside, and a revoked link stops everyone. Keep the group private and never share one permanent link for paid access.
KickThemBot does this for you: it creates each buyer's links with a member limit of one, sends them privately to the buyer, and revokes them when the membership ends. If a buyer leaves the chat while their access is active, their link could admit someone else until it is revoked, so send links only to the buyer and never post them.