Buying Telegram Premium with TON follows the same steps as buying Stars — pick the subscription instead of a Stars amount, pay with TON on TON mainnet, and Premium activates on the account.
A card subscription for Premium often renews automatically by default; paying with TON means checking the option at checkout for whether the same applies.
The TON payment for Premium confirms on TON mainnet the same way a Stars payment would — no separate process for the subscription.
Yes — enter their username at checkout instead of the payer's own, and pay with TON as usual.
No, the subscription activates on their account automatically once the TON payment confirms.