The license is good for three installations as I recall. So no problem with this.
Once you install the PBP and the MPLABX 5.35, the only update you may do is on the compiler itself if and when there will be one. MPLABX will not be updates as the PBP does not support any newer than 5.35 version.
From the settings of the MCS IDE/View/Compile and Program Options, you have two buttons (Default Path and Find Manually...) to direct IDE to the correct MPLABX assembler.
My settings are these on the attached screenshot.
Ioannis
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