Most up to date software has some sort of automatic update system built in, but if you want to check if your software is up to date, follow the instructions below to find out what version you already have. Then click Help again and look for Updates or Check for Updates. That will usually take you to the maker’s download page.
Adobe Photoshop: help / updates
Adobe Lightroom / Capture One / Bibble / DxO: help / check for updates
ACDSee : Help / Product support and resources
Updates to the version you have are almost always free, but an update say from V5 to V6 will have to be paid for. Some manufacturers don’t make that very clear. Also updates will only install if you have a licensed copy of the program already on your PC.