Mosh hit it on the head.
We used to have a plastic tag with banner instructions (DO NOT FOLD - ROLL ONLY!!!) along
with cleaning instructions, our name and number, etc. that we'd use when we had them
sewn after constructing. That and all banners get rolled onto a cardboard core from our
vinyl. They are rolled when the client comes in. We unroll then re-roll and emphasize the need
to always do that when storing.
Don't have those tags anymore and haven't a clue where to get them as the guy in a shop
next to mine made them years ago for us. He died.
We do the same with magnets. Copied the care info from MM (you can get it PDF from their site),
pasted and ganged them in WordPad, printed out a handful, cut them and we STAPLE that
little info sheet to the invoice.
Even if you provide cloth banners if they get folded and placed in the bottom of a box with
a lot of other junk on top they will crease a bit as well. Think of your mom's good tablecloth
she took out on holidays. When first put on the table there were many creases which lessened
with time on the table.