To the OP, unfortunately you've just wasted £11.80 of your money, I'm guessing based on some marketing bumph.
Filling your tyres with nitrogen won't bring you any noticeable benefits. For some reason you think that our tyres now won't go down. Seeing as air is 78% nitrogen anyway, that 22% extra nitrogen you're getting (which is probably not actually 22% because it didn't come bottled anyway) isn't going to stop your tyres going flat.
Also, you only put two thirds of your actual tyre pressure (assuming a tyre pressure of 2bar gauge) in as 'nitrogen' anyway. A true tyre pressure measurement is done in absolute tyre pressure (gauge pressure + atmospheric pressure). As you most likely didn't evacuate your tyres of atmospheric pressure and inflate them from a vacuum, you therefore have 1bar of standard air already in there.
If you wanted any real benefit, you would have had the air let out of your tyres in a humidity controlled environment (with minimal humidity to reduce the moisture content), and then if you'd let the air out quickly, removed any moisture build up around the inner valve area. You would have then inflated our tyres using dry air.
Unfortunately as is said at the start, you've just wasted £11.80 for no benefit.