I want to say to clients to start my chat bot and send me username and password, then I store chat_id of them, and use it whenever I want to send a message to one of them.
Is it possible? or chat_id will be expire?
When a user register on telegram, server choose a unique chat_id for that user! it means the server do this automatically. thus if the user send /start message to your bot for the first time, this chat_id will store on bot database (if you code webhook which demonstrates users statastics)
The answer is if the user doesnt blocked your bot you can successfully send him/her a message. on the other hand if the user had delete accounted no ways suggest for send message to new chat id!
i hope you got it
Can I use chat_id to send message to clients in Telegram bot after a period of time?