When is it a 'real' lie?

I have a bf who has a history of not fully telling the truth about his money issues. Since he wants to live with me and possibly, marry, his truthfulness of this issue is critical. We've been together several years and he knows that until I'm satisfied he is fully transparent, I can't move forward with him. He had been using is elderly mother's credit card for certain items last year when he was unemployed and told me she knew about it. She is essentially destitute and ready to go on Medicaid and has Alzheimer's. The card in question is almost at its max and he pays it with her funds (I think) nominal amounts just to keep the card open for emergencies. He was re-employed 6 months ago and apparently paying his own bills but I learned a magazine subscription he must have ordered last Fall when he was unemployed and used her card, was renewed 1 month ago. I know he sees her bills and makes the modest payments so I assume he saw the charge on the May statement. My question is: I am not aware of whose money the nominal payments on the account came from, but assuming it is his mother's money, isn't this a lie when he has promised not to use it? Even if it is his money that he used to pay his mother's card, wouldn't it be more ethical and responsible for him to have called the vendor and changed the card used once he presumably saw her credit card statement?

Once you marry him, you will be equally responsible for credit cards, loans and other financial obligations that occur during your marriage. If this man is using a destitute disabled woman's credit card, think about the damage he could do to your finances. Even if you don't cosign for the loans, as his wife you will be obligated, or at least have to address these responsibilities. I'd ask some hard questions of this man, and they look for any proof that he is telling the truth. The lying is the least of your problems.

Update I asked him casually about the above. He told me his mothers money only is used to pay the credit card. I didn’t ask about the magazine because his answer made it clear he didn’t pay it. He tells me only the min payment of $50 per month is made to avoid a default. I asked him about the balance and he told me “about $5000”. I know that the credit co require 1% plus interest which is a min payment of 150 not 50 per month. I also confirmed this on my own. I also know the balance is almost $5700 which in my world is not the same as “about $5000”. I asked about whether he uses all his credit cards and he lied telling me he only uses 2 of them but I know he used a 3rd one at least once recently which carries the highest interest rate. Am I blowing things out of proportion or am I correct that all of the above are lies again??!!