apt-get "Couldn't make mmap" error

I have a more-or-less clean 1GB Ubuntu 16.04.3 x64 droplet. I’ve installed Vesta on it, but nothing else. apt-get is failing as follows:

allen@m1:~$ sudo apt-get check
Reading package lists... Error!
E: Couldn't make mmap of 25165824 bytes - DynamicMMap (12: Cannot allocate memory)
E: The package lists or status file could not be parsed or opened.

Get the same results when I try to do anything (not just check). Any idea what’s wrong or how I could address the problem? thanks.


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As it says, “Cannot allocate memory”. Something is using all your memory. Use ps faux.