The biggest factor if they are badly aged there are two indicators. 1) They will stop holding a charge as long as they used to, their mah decreases, and do to mah decrease CDR decreases which causes - 2) due to lower CDR they will feel to warm up a bit more and more often. These are the only 2 real indicators of batteries well maintained that it is time to change them unless you keep a battery log book/log spreadsheet with info like when bought, but most importantly in the logs how many full (2.5 to 3.2 lowest volts up to full 4.2v recharge) and how many half charge cycles (when recharge from 3.6 or higher). Most batteries have a life cycle of 250-300 full charge cycles before being worn out, doing half charge cycles can extend that out to 2/3 more to double the full charge cycles.
Another factor would be how much you abused them with high stress output, being 20amp rated CDR, high stress would be 10amps to 20amps constant duty usage or 2amp to 4amp rapid charges often.
10amps = 10 X 90% control chip efficiency= 9 X 9.6 lowest voltage before mod shutoff = 86.4watts or higher would be high stress.
Basically if you see none of the 3 indicators I've listed, the batteries should be fine, however, if you have noticed any of these or to put your mind at ease, never hurts to err on the side of caution and get replacements. Yet, I've still got batteries, though many used in low wattage (tootle puffing) area, my higher output devices (75plus watts) I have Samsung 25R and Sony VTC4 for, those batteries are still running strong after a year, though are starting to show getting warmer quicker than they used to.