Package means to essentially gather all assets including fonts, images and the InDesign document together for use in sending to the customer.
Copyright law can be a grey area and its always better to play it totally safe than sorry.
Therefore you should only use fonts etc..that the customer has permission to use commercially or is public domain / GPL / OFL OR 100% Free. If you are ever unsure you would be best to buy the original font (as people make duplicates that then are marked as free etc) from the font foundry that created it - especially if your client is a relatively high profile in its market.
It's their reputation ultimately that will suffer far more than yours.
Also this is normally fairly inexpensive if you only use a few styles of the font... especially when compared to the potential lawsuits and fallout etc.
I often use the free fonts for commercial purposes, but i am willing to purchase fonts. The problem is, maybe i misunderstood a bit, i bought font but i also make sure can not send fonts to clients. If packaged fonts in InDesign has its own font folder, and customers can use it to install on their computers, so meaning i sent font meant for guests, and i think the case is similar font embedding, even though i do not resell, trade, redistribution font. I also had email for the support of tykerkit, when i think i need use font from tykekit, and as she/he said, i can only tell customers downloaded font names and places, are not allowed to send to the client font. So i think with other resources too.
To expand on this just a bit. The reason for packaging fonts is not to provide a free font to a printer or client. It's to make sure that someone with a license to use that font is using the identical version that you are.
Like other software, fonts are updated from time to time and using a different version can cause some problems.
Thanks Bob. Great point!