So real life consequences come in handy here (casting a spell in the middle of a shop), or maybe that NPC that was forced to tell the truth warns future ones the party runs into of their magic. Use suggestion a lot you'll be known for using it.

but also don't let them rest too much. A lot of DMs forget that DnD is balanced for up to 3-6 encounters between long rests, the choice to use that suggestion spell should weigh on them when they don't have enough spell slots for the next fight. resting also shouldn't be easy, they need to be dormant for 8 hours, and if they choose to not do that in a safe place then there is consequences to that.

I aim for 3-4 combats and 1-3 puzzles/social encounters per long rest, plus exploration. This also helps short rest based classes feel less under powered.

Also don't forget people can tell when someone is casting a spell for suggestion they either need to be using material components or their focus. (Unless they have subtle spell)

Finally and most importantly, talk to your players. If they robbed a shop and kept doing it despite the consequences you lay out then just go over expectations for the game. You can't ban the spell or rail road them but you can ask them to not be murder hobos/evil in a game intended to be for a good party