I find that, no matter what concealer I use, it always rubs off… so my blemishes never stay covered for long.
I don't know what your beauty routine is, but I suspect that you apply your concealer under your foundation. Even if you have painstakingly covered your blemishes, using foundation afterwards will simply rub it off. So, put on your foundation as normal, to even out your skin tone. Next apply your concealer - use a brush to ensure even and immaculate cover. Set your makeup with a dusting of loose powder, this will stop the oils in your skin from shifting your makeup as the day goes on.