Apt-get :: persistent apt

I am still working with my Frugal install of DSL 3.0 and I still have a hard time trying to get once again what I managed to get very easily three months ago on another computer.
I would like my apt-get installations to be persistent over reboots. Is here another way than, for example, putting /usr/bin in .filetool.lst?

save the .deb's somewhere
then add dpkg -i file.deb in /opt/bootlocal.sh

is there an equivalent to bootlocal.sh for the shutdown, so that I can write a script saving the deb's?

/opt/powerdown.sh

original here.