when ever I go to change the bag in the vacuum cleaner, I am disappointed because either I cannot find where I put them or I have just used the last one....

Well...

here is a good option..

cut the bottom off the full bag, empty it out, and lay it down flat...

then, fold the bottom over and use the clamp to secure it...

this way you can use the same bag several times before the junction seal is worn out....

your vacuum cleaner bags may be a different size and thickness t mine but it is easy to scale the clamp to suit...