It's kinda like asking how many miles you can get out of a set of tires.
For the scanner purposes, it depends on the type of SD card you use. Some memory cards "tolerate" more read/write cycles, such as "High Endurance" cards. Of course none of them last forever and you should figure on replacing them eventually.
Opinions will vary, but I recommend:
https://www.bhphotovideo.com/c/prod...r_032g_an6ia_high_endurance_microsd_32gb.html
At $8.99 per card, they are quite inexpensive (I remember just a couple of years ago, they were $30+).
I am seeing these cards are getting larger in capacity and 32 GB is about the smallest offered these days.