If a company cash a check and i put paid in full in the memo section. Is the account considered paid in full?

Answer 1

no, marking it paid in full means nothing. if the check was for the amount needed to pay off the account it will be paid in full. otherwise you still owe whatever the balance is.

Answer 2

Only if the account "is" paid in full with that check.

If not, then no it would not considered paid in full.