I develop similar products
The lab use of pH electrodes, generally recommend calibrating prior to use. (Before taking readings of sample). No need to recal between samples. Do let the value stablize otherwise you can be reading drift (up to 5 minutes depending on electrode and sample matrix.). Keep the electrode stored in storage solution.
Just be aware the stds do expire so don't buy too much. The other thing bout glass pH electrodes is over time the glass resistance increases (electrode will go bad eventually). This can be accelerated by keeping in hot environment (50ļC is the max that any of the processes to assemble them.)