Procedure to keep a valid text number (textnow ect)

Regarding free text messaging applications like textnow textme ect. Is there a procedure to keep our number valid and operational without being deleted?

Like going to the account once a month, or sending 1 text message with each account every two weeks? Etc.

Do you have a procedure? Thank you

What's wrong with getting physical sims? Considering that you don't need in bulk.