Yes, they're going to have a shelf life on them. Quick way to test it is uninstall the software for the adapter, pull it from the USB port, remove it from Device Manager, then reinstall from scratch: if it's still having issues, the adapter is giving out; if it works fine again, then you're good to go.
Honestly, though, you should never connect a desktop PC to a router wirelessly. Wireless is best for devices that you don't want to be tied down to a set location (laptops, tablets, MP3 players, smartphones, etc.), or devices that are far enough away from the router that you don't want the time/effort/money to fish Ethernet cables through your walls (Internet-connected TVs, Roku/Chromecast, game consoles, etc.) -- or worse, running the cable over/under the carpet through a room & down the hallway. But by definition, your desktop PC is not a moveable PC (you're going to set it up in the spot where you plan on using it 100% of the time), & ideally your router should be in the same room (if not in the same computer desk) as the router. If at all possible, consider putting the desktop within 5-6 feet of the router, & hardwiring into 1 of the LAN ports on the back. You'll free up a USB port on the machine, & you'll have a dedicated line you can use for testing if the other devices have wireless issues.