I forgot to buy a microSD
Can and how do i run angstrom without MicroSD? I have microUSB.
maybe not.
You can run the Angstrom distribution that came with your BBB via the eMMC. But there is no way to update it or run another OS without a microSD.
If you have a smartphone or other device with a microSD card then you could always temporarily borrow it. Just backup you stuff first. 