Most vendors beyond the $10 120G specials will have a TBW parameter on their spec sheet. This is the estimated number of Terabytes Written before failure of the SSD begins.

Using smartctl for various Unix systems, you can read the values of most SSD's and calculate the remaining lifetime.

apt install smartmontools
# record number of Logical Bytes that makes up a sector
smartctl /dev/sda -a |grep "Sector Size"
# record Raw Value (rightmost column) as Number of Writes
smartctl -a /dev/sda | grep '241 Host_Writes'

Now, multiply the above two values (rightmost column on both). That is the number of bytes written to the SSD since it was manufactured.

You can find the make/model of the drive with the following two commands:

smartctl -a /dev/sda | grep '^Model Family:'
smartctl -a /dev/sda | grep '^Device Model:'

and go to the vendors web site to see what they estimate is the lifetime.

NOTE: some vendors do not include ID 241 in their output, so all you can do is guess. One good thing to try is simply take the output of smartctl -a and pipe it to less, then read through it (not that big).