Mailing Sticker Orders. Stamps with Shipping label or just Stamps?

[WeFlaps]

Hello there!

I'm in the process of setting up a merch store to sell stickers, magnets and small envelope things.

I've had a Patreon for a year now and sold stickers and magnets there at a $9 tier succesfully and I did that by envelope and stamps. Sometimes I have extra product sent by the vendor and I want to sell it on a merch store to the rest of the audience.

I'm curious if I truly need to do shipping labels or if I can just continue with stamps as I have with patreon. I know shipping labels are meant for tracking, but I already have a crazy time with self employment work, I don't want to over complicate my mailing procedure. If I just stick with mailing stickers in envelope and stamped myself, is there anything I have to worry about besides no tracking information?