The K$^{\pm}$K$^{\pm}$ experimental correlation functions (green solid circles) as function of the invariant pair relative momentum $q_\mathrm{\rm inv}$ in pp collisions at $\sqrt{s}=13$ TeV for the raw multiplicity $N_{\rm trk}$ intervals of (1--18), (19--30), and ($>30$) in the (0.15--0.5) GeV$/c$ and (0.5--1.2) GeV$/c$ $k_{\rm T}$ intervals. A sphericity selection of $S_{\rm T} > 0.7$ is applied. The data are compared with PYTHIA 8 calculations shown by blue crosses. The PYTHIA 8 calculations are approximated with a second-order polynomial (red curves). The error bars represent the statistical uncertainties, while the systematic uncertainties are negligible.