patents what happens when they have not

building

been renewed. my partner had an invention. managed to sell a few but then was not at the time able to financially get himself more involved in his project and got back into work. as he sold quite a few products and the product was patented at the time he wonders whether he should look into renewing a patent to carry on. does anyone know how it works. and what are the options for getting funding on this sort of thing as i believe it cost him about £3,500 the first time round. thanks in advance.
the patent was first done around 5 years ago.

xycom1

Once the patent expires, anyone can copy the design and sell it on their own - like medicines. The company that invents the drug patents it for a certain amount of time (e.g. 20 years), makes stacks of money off it, then once the patent has expired 'anybody' can copy it and sell their own version (with drugs, subject to regulatory clearance, etc.).